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| author | Nathan Huckleberry <nhuck@google.com> | 2022-07-22 11:38:23 +0200 |
|---|---|---|
| committer | Mike Snitzer <snitzer@kernel.org> | 2022-08-04 19:50:40 +0200 |
| commit | 5721d4e5a9cdb148f681a004ae5748890a0e2d90 (patch) | |
| tree | f5247abca044ef89ce7fe5a2a887e5edfb4cd68f /drivers/md/dm-verity.h | |
| parent | dm bufio: Add DM_BUFIO_CLIENT_NO_SLEEP flag (diff) | |
| download | linux-5721d4e5a9cdb148f681a004ae5748890a0e2d90.tar.xz linux-5721d4e5a9cdb148f681a004ae5748890a0e2d90.zip | |
dm verity: Add optional "try_verify_in_tasklet" feature
Using tasklets for disk verification can reduce IO latency. When there
are accelerated hash instructions it is often better to compute the
hash immediately using a tasklet rather than deferring verification to
a work-queue. This reduces time spent waiting to schedule work-queue
jobs, but requires spending slightly more time in interrupt context.
If the dm-bufio cache does not have the required hashes we fallback to
the work-queue implementation. FEC is only possible using work-queue
because code to support the FEC feature may sleep.
The following shows a speed comparison of random reads on a dm-verity
device. The dm-verity device uses a 1G ramdisk for data and a 1G
ramdisk for hashes. One test was run using tasklets and one test was
run using the existing work-queue solution. Both tests were run when
the dm-bufio cache was hot. The tasklet implementation performs
significantly better since there is no time spent waiting for
work-queue jobs to be scheduled.
READ: bw=181MiB/s (190MB/s), 181MiB/s-181MiB/s (190MB/s-190MB/s),
io=512MiB (537MB), run=2827-2827msec
READ: bw=23.6MiB/s (24.8MB/s), 23.6MiB/s-23.6MiB/s (24.8MB/s-24.8MB/s),
io=512MiB (537MB), run=21688-21688msec
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Diffstat (limited to 'drivers/md/dm-verity.h')
| -rw-r--r-- | drivers/md/dm-verity.h | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/md/dm-verity.h b/drivers/md/dm-verity.h index 4e769d13473a..fb92b22a6404 100644 --- a/drivers/md/dm-verity.h +++ b/drivers/md/dm-verity.h @@ -13,6 +13,7 @@ #include <linux/dm-bufio.h> #include <linux/device-mapper.h> +#include <linux/interrupt.h> #include <crypto/hash.h> #define DM_VERITY_MAX_LEVELS 63 @@ -51,9 +52,10 @@ struct dm_verity { unsigned char hash_per_block_bits; /* log2(hashes in hash block) */ unsigned char levels; /* the number of tree levels */ unsigned char version; + bool hash_failed:1; /* set if hash of any block failed */ + bool use_tasklet:1; /* try to verify in tasklet before work-queue */ unsigned digest_size; /* digest size for the current hash algorithm */ unsigned int ahash_reqsize;/* the size of temporary space for crypto */ - int hash_failed; /* set to 1 if hash of any block failed */ enum verity_mode mode; /* mode for handling verification errors */ unsigned corrupted_errs;/* Number of errors for corrupted blocks */ @@ -76,10 +78,12 @@ struct dm_verity_io { sector_t block; unsigned n_blocks; + bool in_tasklet; struct bvec_iter iter; struct work_struct work; + struct tasklet_struct tasklet; /* * Three variably-size fields follow this struct: |