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* rcuscale: Remove redundant WARN_ON_ONCE() splatUladzislau Rezki (Sony)2024-11-151-2/+0
| | | | | | | | | | | | | There are two places where WARN_ON_ONCE() is called two times in the error paths. One which is encapsulated into if() condition and another one, which is unnecessary, is placed in the brackets. Remove an extra WARN_ON_ONCE() splat which is in brackets. Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
* rcuscale: Do a proper cleanup if kfree_scale_init() failsUladzislau Rezki (Sony)2024-11-151-2/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A static analyzer for C, Smatch, reports and triggers below warnings: kernel/rcu/rcuscale.c:1215 rcu_scale_init() warn: inconsistent returns 'global &fullstop_mutex'. The checker complains about, we do not unlock the "fullstop_mutex" mutex, in case of hitting below error path: <snip> ... if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start < 2 * HZ)) { pr_alert("ERROR: call_rcu() CBs are not being lazy as expected!\n"); WARN_ON_ONCE(1); return -1; ^^^^^^^^^^ ... <snip> it happens because "-1" is returned right away instead of doing a proper unwinding. Fix it by jumping to "unwind" label instead of returning -1. Reported-by: Dan Carpenter <dan.carpenter@linaro.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com> Closes: https://lore.kernel.org/rcu/ZxfTrHuEGtgnOYWp@pc636/T/ Fixes: 084e04fff160 ("rcuscale: Add laziness and kfree tests") Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
* rcuscale: Count outstanding callbacks per-task rather than per-CPUPaul E. McKenney2024-08-141-4/+6
| | | | | | | | | | | | | | | | The current rcu_scale_writer() asynchronous grace-period testing uses a per-CPU counter to track the number of outstanding callbacks. This is subject to CPU-imbalance errors when tasks migrate from one CPU to another between the time that the counter is incremented and the callback is queued, and additionally in kernels configured such that callbacks can be invoked on some CPU other than the one that queued it. This commit therefore arranges for per-task callback counts, thus avoiding any issues with migration of either tasks or callbacks. Reported-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
* rcuscale: NULL out top-level pointers to heap memoryPaul E. McKenney2024-08-141-0/+5
| | | | | | | | | | | | | Currently, if someone modprobes and rmmods rcuscale successfully, but the next run errors out during the modprobe, non-NULL pointers to freed memory will remain. If the run after that also errors out during the modprobe, there will be double-free bugs. This commit therefore NULLs out top-level pointers to memory that has just been freed. Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
* rcuscale: Use special allocator for rcu_scale_writer()Paul E. McKenney2024-08-141-10/+113
| | | | | | | | | | | The rcu_scale_writer() function needs only a fixed number of rcu_head structures per kthread, which means that a trivial allocator suffices. This commit therefore uses an llist-based allocator using a fixed array of structures per kthread. This allows aggressive testing of RCU performance without stressing the slab allocators. Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
* rcuscale: Make rcu_scale_writer() tolerate repeated GFP_KERNEL failurePaul E. McKenney2024-08-141-3/+6
| | | | | | | | | | | | | | | | | | | | Under some conditions, kmalloc(GFP_KERNEL) allocations have been observed to repeatedly fail. This situation has been observed to cause one of the rcu_scale_writer() instances to loop indefinitely retrying memory allocation for an asynchronous grace-period primitive. The problem is that if memory is short, all the other instances will allocate all available memory before the looping task is awakened from its rcu_barrier*() call. This in turn results in hangs, so that rcuscale fails to complete. This commit therefore removes the tight retry loop, so that when this condition occurs, the affected task is still passing through the full loop with its full set of termination checks. This spreads the risk of indefinite memory-allocation retry failures across all instances of rcu_scale_writer() tasks, which in turn prevents the hangs. Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
* rcuscale: Make all writer tasks report upon hangPaul E. McKenney2024-08-141-0/+6
| | | | | | | | This commit causes all writer tasks to provide a brief report after a hang has been reported, spaced at one-second intervals. Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
* rcuscale: Provide clear error when async specified without primitivesPaul E. McKenney2024-08-141-2/+2
| | | | | | | | | | | Currently, if the rcuscale module's async module parameter is specified for RCU implementations that do not have async primitives such as RCU Tasks Rude (which now lacks a call_rcu_tasks_rude() function), there will be a series of splats due to calls to a NULL pointer. This commit therefore warns of this situation, but switches to non-async testing. Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
* rcuscale: Print detailed grace-period and barrier diagnosticsPaul E. McKenney2024-08-141-0/+18
| | | | | | | | | | | | | This commit uses the new rcu_tasks_torture_stats_print(), rcu_tasks_trace_torture_stats_print(), and rcu_tasks_rude_torture_stats_print() functions in order to provide detailed diagnostics on grace-period, callback, and barrier state when rcu_scale_writer() hangs. [ paulmck: Apply kernel test robot feedback. ] Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
* rcuscale: Dump grace-period statistics when rcu_scale_writer() stallsPaul E. McKenney2024-08-141-0/+10
| | | | | | | | | This commit adds a .stats function pointer to the rcu_scale_ops structure, and if this is non-NULL, it is invoked after stack traces are dumped in response to a rcu_scale_writer() stall. Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
* rcuscale: Dump stacks of stalled rcu_scale_writer() instancesPaul E. McKenney2024-08-141-2/+21
| | | | | | | | | | | | | This commit improves debuggability by dumping the stacks of rcu_scale_writer() instances that have not completed in a reasonable timeframe. These stacks are dumped remotely, but they will be accurate in the thus-far common case where the stalled rcu_scale_writer() instances are blocked. [ paulmck: Apply kernel test robot feedback. ] Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
* rcuscale: Save a few lines with whitespace-only changePaul E. McKenney2024-08-141-7/+3
| | | | | | | | This whitespace-only commit fuses a few lines of code, taking advantage of the newish 100-character-per-line limit to save a few lines of code. Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
* rcuscale: Stop testing RCU Tasks Rude asynchronous APIsPaul E. McKenney2024-08-141-2/+0
| | | | | | | | | | | | The call_rcu_tasks_rude() and rcu_barrier_tasks_rude() APIs are currently unused. Furthermore, the idea is to get rid of RCU Tasks Rude entirely once all architectures have their deep-idle and entry/exit code correctly marked as inline or noinstr. As a step towards this goal, this commit therefore removes these two functions from rcuscale testing. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
* rcutorture: Add missing MODULE_DESCRIPTION() macrosJeff Johnson2024-06-061-0/+1
| | | | | | | | | | | Fix the following 'make W=1' warnings: WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/rcu/rcutorture.o WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/rcu/rcuscale.o WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/rcu/refscale.o Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcu: Rename jiffies_till_flush to jiffies_lazy_flushFrederic Weisbecker2024-02-141-3/+3
| | | | | | | | | | | | | | The variable name jiffies_till_flush is too generic and therefore: * It may shadow a global variable * It doesn't tell on what it operates Make the name more precise, along with the related APIs. Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
* rcuscale: Move rcu_scale_writer() schedule_timeout_uninterruptible() to _idle()Zqiang2023-07-151-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The rcuscale.holdoff module parameter can be used to delay the start of rcu_scale_writer() kthread. However, the hung-task timeout will trigger when the timeout specified by rcuscale.holdoff is greater than hung_task_timeout_secs: runqemu kvm nographic slirp qemuparams="-smp 4 -m 2048M" bootparams="rcuscale.shutdown=0 rcuscale.holdoff=300" [ 247.071753] INFO: task rcu_scale_write:59 blocked for more than 122 seconds. [ 247.072529] Not tainted 6.4.0-rc1-00134-gb9ed6de8d4ff #7 [ 247.073400] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 247.074331] task:rcu_scale_write state:D stack:30144 pid:59 ppid:2 flags:0x00004000 [ 247.075346] Call Trace: [ 247.075660] <TASK> [ 247.075965] __schedule+0x635/0x1280 [ 247.076448] ? __pfx___schedule+0x10/0x10 [ 247.076967] ? schedule_timeout+0x2dc/0x4d0 [ 247.077471] ? __pfx_lock_release+0x10/0x10 [ 247.078018] ? enqueue_timer+0xe2/0x220 [ 247.078522] schedule+0x84/0x120 [ 247.078957] schedule_timeout+0x2e1/0x4d0 [ 247.079447] ? __pfx_schedule_timeout+0x10/0x10 [ 247.080032] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.080591] ? __pfx_process_timeout+0x10/0x10 [ 247.081163] ? __pfx_sched_set_fifo_low+0x10/0x10 [ 247.081760] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.082287] rcu_scale_writer+0x6b1/0x7f0 [ 247.082773] ? mark_held_locks+0x29/0xa0 [ 247.083252] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.083865] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.084412] kthread+0x179/0x1c0 [ 247.084759] ? __pfx_kthread+0x10/0x10 [ 247.085098] ret_from_fork+0x2c/0x50 [ 247.085433] </TASK> This commit therefore replaces schedule_timeout_uninterruptible() with schedule_timeout_idle(). Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: fix building with RCU_TINYArnd Bergmann2023-07-151-2/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Both the CONFIG_TASKS_RCU and CONFIG_TASKS_RUDE_RCU options are broken when RCU_TINY is enabled as well, as some functions are missing a declaration. In file included from kernel/rcu/update.c:649: kernel/rcu/tasks.h:1271:21: error: no previous prototype for 'get_rcu_tasks_rude_gp_kthread' [-Werror=missing-prototypes] 1271 | struct task_struct *get_rcu_tasks_rude_gp_kthread(void) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/rcu/rcuscale.c:330:27: error: 'get_rcu_tasks_rude_gp_kthread' undeclared here (not in a function); did you mean 'get_rcu_tasks_trace_gp_kthread'? 330 | .rso_gp_kthread = get_rcu_tasks_rude_gp_kthread, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | get_rcu_tasks_trace_gp_kthread In file included from /home/arnd/arm-soc/kernel/rcu/update.c:649: kernel/rcu/tasks.h:1113:21: error: no previous prototype for 'get_rcu_tasks_gp_kthread' [-Werror=missing-prototypes] 1113 | struct task_struct *get_rcu_tasks_gp_kthread(void) | ^~~~~~~~~~~~~~~~~~~~~~~~ Also, building with CONFIG_TASKS_RUDE_RCU but not CONFIG_TASKS_RCU is broken because of some missing stub functions: kernel/rcu/rcuscale.c:322:27: error: 'tasks_scale_read_lock' undeclared here (not in a function); did you mean 'srcu_scale_read_lock'? 322 | .readlock = tasks_scale_read_lock, | ^~~~~~~~~~~~~~~~~~~~~ | srcu_scale_read_lock kernel/rcu/rcuscale.c:323:27: error: 'tasks_scale_read_unlock' undeclared here (not in a function); did you mean 'srcu_scale_read_unlock'? 323 | .readunlock = tasks_scale_read_unlock, | ^~~~~~~~~~~~~~~~~~~~~~~ | srcu_scale_read_unlock Move the declarations outside of the RCU_TINY #ifdef and duplicate the shared stub functions to address all of the above. Fixes: 88d7ff818f0ce ("rcuscale: Add RCU Tasks Rude testing") Fixes: 755f1c5eb416b ("rcuscale: Measure RCU Tasks Trace grace-period kthread CPU time") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Add RCU Tasks Rude testingPaul E. McKenney2023-07-151-1/+30
| | | | | | Add a "tasks-rude" option to the rcuscale.scale_type module parameter. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Measure RCU Tasks Trace grace-period kthread CPU timePaul E. McKenney2023-07-151-0/+1
| | | | | | | | | | | | | | | This commit causes RCU Tasks Trace to output the CPU time consumed by its grace-period kthread. The CPU time is whatever is in the designated task's current->stime field, and thus is controlled by whatever CPU-time accounting scheme is in effect. This output appears in microseconds as follows on the console: rcu_scale: Grace-period kthread CPU time: 42367.037 [ paulmck: Apply Willy Tarreau feedback. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Measure grace-period kthread CPU timePaul E. McKenney2023-07-151-0/+21
| | | | | | | | | | | | | | | | This commit adds the ability to output the CPU time consumed by the grace-period kthread for the RCU variant under test. The CPU time is whatever is in the designated task's current->stime field, and thus is controlled by whatever CPU-time accounting scheme is in effect. This output appears in microseconds as follows on the console: rcu_scale: Grace-period kthread CPU time: 42367.037 [ paulmck: Apply feedback from Stephen Rothwell and kernel test robot. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Tested-by: Yujie Liu <yujie.liu@intel.com>
* rcuscale: Print out full set of kfree_rcu parametersPaul E. McKenney2023-07-151-0/+4
| | | | | Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
* rcuscale: Print out full set of module parametersPaul E. McKenney2023-07-151-2/+2
| | | | Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Add minruntime module parameterPaul E. McKenney2023-07-151-1/+4
| | | | | | | | | | | By default, rcuscale collects only 100 points of data per writer, but arranging for all kthreads to be actively collecting (if not recording) data during the time that any kthread might be recording. This works well, but does not allow much time to bring external performance tools to bear. This commit therefore adds a minruntime module parameter that specifies a minimum data-collection interval in seconds. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Fix gp_async_max typo: s/reader/writer/Paul E. McKenney2023-07-151-1/+1
| | | | Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Permit blocking delays between writersPaul E. McKenney2023-07-151-0/+4
| | | | | | | | | Some workloads do isolated RCU work, and this can affect operation latencies. This commit therefore adds a writer_holdoff_jiffies module parameter that causes writers to block for the specified number of jiffies between each pair of consecutive write-side operations. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcu/rcuscale: Stop kfree_scale_thread thread(s) after unloading rcuscaleQiuxu Zhuo2023-05-111-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Running the 'kfree_rcu_test' test case [1] results in a splat [2]. The root cause is the kfree_scale_thread thread(s) continue running after unloading the rcuscale module. This commit fixes that isue by invoking kfree_scale_cleanup() from rcu_scale_cleanup() when removing the rcuscale module. [1] modprobe rcuscale kfree_rcu_test=1 // After some time rmmod rcuscale rmmod torture [2] BUG: unable to handle page fault for address: ffffffffc0601a87 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page PGD 11de4f067 P4D 11de4f067 PUD 11de51067 PMD 112f4d067 PTE 0 Oops: 0010 [#1] PREEMPT SMP NOPTI CPU: 1 PID: 1798 Comm: kfree_scale_thr Not tainted 6.3.0-rc1-rcu+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015 RIP: 0010:0xffffffffc0601a87 Code: Unable to access opcode bytes at 0xffffffffc0601a5d. RSP: 0018:ffffb25bc2e57e18 EFLAGS: 00010297 RAX: 0000000000000000 RBX: ffffffffc061f0b6 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff962fd0de RDI: ffffffff962fd0de RBP: ffffb25bc2e57ea8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000000 R14: 000000000000000a R15: 00000000001c1dbe FS: 0000000000000000(0000) GS:ffff921fa2200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffc0601a5d CR3: 000000011de4c006 CR4: 0000000000370ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ? kvfree_call_rcu+0xf0/0x3a0 ? kthread+0xf3/0x120 ? kthread_complete_and_exit+0x20/0x20 ? ret_from_fork+0x1f/0x30 </TASK> Modules linked in: rfkill sunrpc ... [last unloaded: torture] CR2: ffffffffc0601a87 ---[ end trace 0000000000000000 ]--- Fixes: e6e78b004fa7 ("rcuperf: Add kfree_rcu() performance Tests") Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcu/rcuscale: Move rcu_scale_*() after kfree_scale_cleanup()Qiuxu Zhuo2023-05-111-97/+97
| | | | | | | | | | | This code-movement-only commit moves the rcu_scale_cleanup() and rcu_scale_shutdown() functions to follow kfree_scale_cleanup(). This is code movement is in preparation for a bug-fix patch that invokes kfree_scale_cleanup() from rcu_scale_cleanup(). Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
*-. Merge branches 'rcu/staging-core', 'rcu/staging-docs' and ↵Joel Fernandes (Google)2023-04-051-5/+4
|\ \ | | | | | | | | | 'rcu/staging-kfree', remote-tracking branches 'paul/srcu-cf.2023.04.04a', 'fbq/rcu/lockdep.2023.03.27a' and 'fbq/rcu/rcutorture.2023.03.20a' into rcu/staging
| | * rcuscale: Move shutdown from wait_event() to wait_event_idle()Paul E. McKenney2023-03-201-4/+3
| |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The rcu_scale_shutdown() and kfree_scale_shutdown() kthreads/functions use wait_event() to wait for the rcuscale test to complete. However, each updater thread in such a test waits for at least 100 grace periods. If each grace period takes more than 1.2 seconds, which is long, but not insanely so, this can trigger the hung-task timeout. This commit therefore replaces those wait_event() calls with calls to wait_event_idle(), which do not trigger the hung-task timeout. Reported-by: kernel test robot <yujie.liu@intel.com> Reported-by: Liam Howlett <liam.howlett@oracle.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Tested-by: Yujie Liu <yujie.liu@intel.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
| * rcuscale: Rename kfree_rcu() to kfree_rcu_mightsleep()Uladzislau Rezki (Sony)2023-04-051-1/+1
|/ | | | | | | | | | | | | The kfree_rcu() and kvfree_rcu() macros' single-argument forms are deprecated. Therefore switch to the new kfree_rcu_mightsleep() and kvfree_rcu_mightsleep() variants. The goal is to avoid accidental use of the single-argument forms, which can introduce functionality bugs in atomic contexts and latency bugs in non-atomic contexts. Acked-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
* rcu/rcuscale: Use call_rcu_hurry() for async reader testJoel Fernandes (Google)2022-11-291-1/+1
| | | | | | | | | | | rcuscale uses call_rcu() to queue async readers. With recent changes to save power, the test will have fewer async readers in flight. Use the call_rcu_hurry() API instead to revert to the old behavior. [ paulmck: Apply s/call_rcu_flush/call_rcu_hurry/ feedback from Tejun Heo. ] Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Add laziness and kfree testsJoel Fernandes (Google)2022-11-291-2/+65
| | | | | | | | | | | | | This commit adds 2 tests to rcuscale. The first one is a startup test to check whether we are not too lazy or too hard working. The second one causes kfree_rcu() itself to use call_rcu() and checks memory pressure. Testing indicates that the new call_rcu() keeps memory pressure under control roughly as well as does kfree_rcu(). [ paulmck: Apply checkpatch feedback. ] Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Fix smp_processor_id()-in-preemptible warningsZqiang2022-06-221-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Systems built with CONFIG_DEBUG_PREEMPT=y can trigger the following BUG while running the rcuscale performance test: BUG: using smp_processor_id() in preemptible [00000000] code: rcu_scale_write/69 CPU: 0 PID: 66 Comm: rcu_scale_write Not tainted 5.18.0-rc7-next-20220517-yoctodev-standard+ caller is debug_smp_processor_id+0x17/0x20 Call Trace: <TASK> dump_stack_lvl+0x49/0x5e dump_stack+0x10/0x12 check_preemption_disabled+0xdf/0xf0 debug_smp_processor_id+0x17/0x20 rcu_scale_writer+0x2b5/0x580 kthread+0x177/0x1b0 ret_from_fork+0x22/0x30 </TASK> Reproduction method: runqemu kvm slirp nographic qemuparams="-m 4096 -smp 8" bootparams="isolcpus=2,3 nohz_full=2,3 rcu_nocbs=2,3 rcutree.dump_tree=1 rcuscale.shutdown=false rcuscale.gp_async=true" -d The problem is that the rcu_scale_writer() kthreads fail to set the PF_NO_SETAFFINITY flags, which causes is_percpu_thread() to assume that the kthread's affinity might change at any time, thus the BUG noted above. This commit therefore causes rcu_scale_writer() to set PF_NO_SETAFFINITY in its kthread's ->flags field, thus preventing this BUG. Signed-off-by: Zqiang <qiang1.zhang@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Allow rcuscale without RCU Tasks Rude/TracePaul E. McKenney2022-04-211-1/+11
| | | | | | | | | | | | Currently, a CONFIG_PREEMPT_NONE=y kernel substitutes normal RCU for RCU Tasks Rude and RCU Tasks Trace. Unless that kernel builds rcuscale, whether built-in or as a module, in which case these RCU Tasks flavors are (unnecessarily) built in. This both increases kernel size and increases the complexity of certain tracing operations. This commit therefore decouples the presence of rcuscale from the presence of RCU Tasks Rude and RCU Tasks Trace. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Allow rcuscale without RCU TasksPaul E. McKenney2022-04-211-1/+11
| | | | | | | | | | | Currently, a CONFIG_PREEMPT_NONE=y kernel substitutes normal RCU for RCU Tasks. Unless that kernel builds rcuscale, whether built-in or as a module, in which case RCU Tasks is (unnecessarily) built. This both increases kernel size and increases the complexity of certain tracing operations. This commit therefore decouples the presence of rcuscale from the presence of RCU Tasks. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Always log error messageLi Zhijian2021-12-081-7/+7
| | | | | | | | Unconditionally log messages corresponding to errors. Acked-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Li Zhijian <zhijianx.li@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Warn on individual rcu_scale_init() error conditionsPaul E. McKenney2021-09-141-5/+5
| | | | | | | | | | | When running rcuscale as a module, any rcu_scale_init() issues will be reflected in the error code from modprobe or insmod, as the case may be. However, these error codes are not available when running rcuscale built-in, for example, when using the kvm.sh script. This commit therefore adds WARN_ON_ONCE() to allow distinguishing rcu_scale_init() errors when running rcuscale built-in. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Console output claims too few grace periodsJiangong.Han2021-07-271-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The rcuscale console output claims N grace periods, numbered from zero to N, which means that there were really N+1 grace periods. The root cause of this bug is that rcu_scale_writer() stores the number of the last grace period (numbered from zero) into writer_n_durations[me] instead of the number of grace periods. This commit therefore assigns the actual number of grace periods to writer_n_durations[me], and also makes the corresponding adjustment to the loop outputting per-grace-period measurements. Sample of old console output: rcu-scale: writer 0 gps: 133 ...... rcu-scale: 0 writer-duration: 0 44003961 rcu-scale: 0 writer-duration: 1 32003582 ...... rcu-scale: 0 writer-duration: 132 28004391 rcu-scale: 0 writer-duration: 133 27996410 Sample of new console output: rcu-scale: writer 0 gps: 134 ...... rcu-scale: 0 writer-duration: 0 44003961 rcu-scale: 0 writer-duration: 1 32003582 ...... rcu-scale: 0 writer-duration: 132 28004391 rcu-scale: 0 writer-duration: 133 27996410 Signed-off-by: Jiangong.Han <jiangong.han@windriver.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Add kfree_rcu() single-argument scale testUladzislau Rezki (Sony)2021-03-081-1/+14
| | | | | | | | | | | | | | | | | | The single-argument variant of kfree_rcu() is currently not tested by any member of the rcutoture test suite. This commit therefore adds rcuscale code to test it. This testing is controlled by two new boolean module parameters, kfree_rcu_test_single and kfree_rcu_test_double. If one is set and the other not, only the corresponding variant is tested, otherwise both are tested, with the variant to be tested determined randomly on each invocation. Both of these module parameters are initialized to false, so setting either to true will test only that variant. Suggested-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Prevent hangs for invalid argumentsPaul E. McKenney2020-11-071-1/+4
| | | | | | | | | | | | If an rcuscale torture-test run is given a bad kvm.sh argument, the test will complain to the console, which is good. What is bad is that from the user's perspective, it will just hang for the time specified by the --duration argument. This commit therefore forces an immediate kernel shutdown if a rcu_scale_init()-time error occurs, thus avoiding the appearance of a hang. It also forces a console splat in this case to clearly indicate the presence of an error. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuscale: Add RCU Tasks TracePaul E. McKenney2020-11-071-1/+31
| | | | | | | | This commit adds the ability to test performance and scalability of RCU Tasks Trace updaters. Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcuperf: Change rcuperf to rcuscalePaul E. McKenney2020-08-251-0/+853
This commit further avoids conflation of rcuperf with the kernel's perf feature by renaming kernel/rcu/rcuperf.c to kernel/rcu/rcuscale.c, and also by similarly renaming the functions and variables inside this file. This has the side effect of changing the names of the kernel boot parameters, so kernel-parameters.txt and ver_functions.sh are also updated. The rcutorture --torture type was also updated from rcuperf to rcuscale. [ paulmck: Fix bugs located by Stephen Rothwell. ] Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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