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| author | Dave Hansen <dave@sr71.net> | 2015-07-17 12:28:11 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-07-18 03:42:35 +0200 |
| commit | 0c8c0f03e3a292e031596484275c14cf39c0ab7a (patch) | |
| tree | c1d012c83722e9fa3b7bc152e64697828f6cbc35 /include | |
| parent | x86/entry/64, x86/nmi/64: Add CONFIG_DEBUG_ENTRY NMI testing code (diff) | |
| download | linux-0c8c0f03e3a292e031596484275c14cf39c0ab7a.tar.xz linux-0c8c0f03e3a292e031596484275c14cf39c0ab7a.zip | |
x86/fpu, sched: Dynamically allocate 'struct fpu'
The FPU rewrite removed the dynamic allocations of 'struct fpu'.
But, this potentially wastes massive amounts of memory (2k per
task on systems that do not have AVX-512 for instance).
Instead of having a separate slab, this patch just appends the
space that we need to the 'task_struct' which we dynamically
allocate already. This saves from doing an extra slab
allocation at fork().
The only real downside here is that we have to stick everything
and the end of the task_struct. But, I think the
BUILD_BUG_ON()s I stuck in there should keep that from being too
fragile.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1437128892-9831-2-git-send-email-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/sched.h | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index ae21f1591615..e43a41d892b6 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1522,8 +1522,6 @@ struct task_struct { /* hung task detection */ unsigned long last_switch_count; #endif -/* CPU-specific state of this task */ - struct thread_struct thread; /* filesystem information */ struct fs_struct *fs; /* open file information */ @@ -1778,8 +1776,18 @@ struct task_struct { unsigned long task_state_change; #endif int pagefault_disabled; +/* CPU-specific state of this task */ + struct thread_struct thread; +/* + * WARNING: on x86, 'thread_struct' contains a variable-sized + * structure. It *MUST* be at the end of 'task_struct'. + * + * Do not put anything below here! + */ }; +extern int arch_task_struct_size(void); + /* Future-safe accessor for struct task_struct's cpus_allowed. */ #define tsk_cpus_allowed(tsk) (&(tsk)->cpus_allowed) |