xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

BACKPORT: dm verity: enable WQ_HIGHPRI on verify_wq

Browse Source 
WQ_HIGHPRI increases throughput and decreases disk latency when using
dm-verity. This is important in Android for camera startup speed.

The following tests were run by doing 60 seconds of random reads using
a dm-verity device backed by two ramdisks.

Without WQ_HIGHPRI
lat (usec): min=13, max=3947, avg=69.53, stdev=50.55
READ: bw=51.1MiB/s (53.6MB/s), 51.1MiB/s-51.1MiB/s (53.6MB/s-53.6MB/s)

With WQ_HIGHPRI:
lat (usec): min=13, max=7854, avg=31.15, stdev=30.42
READ: bw=116MiB/s (121MB/s), 116MiB/s-116MiB/s (121MB/s-121MB/s)

Further testing was done by measuring how long it takes to open a
camera on an Android device.

Without WQ_HIGHPRI
Total verity work queue wait times (ms):
880.960, 789.517, 898.852

With WQ_HIGHPRI:
Total verity work queue wait times (ms):
528.824, 439.191, 433.300

The average time to open the camera is reduced by 350ms (or 40-50%).

Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

Bug: 233247259
(cherry picked from commit afd41fff9c73ccc3757e94ad727d2a9ac4d7f6cb)
[nhuck: Resolved minor conflict in drivers/md/dm-verity-target.c ]
(cherry picked from https://android-review.googlesource.com/q/commit:fd4631f8568f5bf16ac5c8b0686d40fad6e4e047)
Merged-In: I7d600c924b4a3e793b9a26c2852139683061a831

Bug: 279521578
Change-Id: Ib858d388aa24e4a625085804c097ad66aa179a14
This commit is contained in:
Nathan Huckleberry
2022-08-30 18:44:44 +00:00
committed by Will Deacon
parent 004c469370
commit 3de420d372
1 changed files with 13 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/md/dm-verity-target.c
View File

@@ -993,6 +993,7 @@ static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
struct dm_verity_sig_opts verify_args = {0};
struct dm_arg_set as;
unsigned int num;
unsigned int wq_flags;
unsigned long long num_ll;
int r;
int i;
@@ -1220,7 +1221,18 @@ static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
}
/* WQ_UNBOUND greatly improves performance when running on ramdisk */
v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
wq_flags = WQ_MEM_RECLAIM | WQ_UNBOUND;
/*
* Using WQ_HIGHPRI improves throughput and completion latency by
* reducing wait times when reading from a dm-verity device.
*
* Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
* allows verify_wq to preempt softirq since verification in tasklet
* will fall-back to using it for error handling (or if the bufio cache
* doesn't have required hashes).
*/
wq_flags |= WQ_HIGHPRI;
v->verify_wq = alloc_workqueue("kverityd", wq_flags, num_online_cpus());
if (!v->verify_wq) {
ti->error = "Cannot allocate workqueue";
r = -ENOMEM;