[lkml]   [2020]   [Mar]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH v1 3/3] virtio-balloon: Switch back to OOM handler for VIRTIO_BALLOON_F_DEFLATE_ON_OOM
On Sat, Mar 07, 2020 at 08:47:25PM -0800, Tyler Sanderson wrote:
> Tested-by: Tyler Sanderson <>
> Test setup: VM with 16 CPU, 64GB RAM. Running Debian 10. We have a 42
> GB file full of random bytes that we continually cat to /dev/null.
> This fills the page cache as the file is read. Meanwhile we trigger
> the balloon to inflate, with a target size of 53 GB. This setup causes
> the balloon inflation to pressure the page cache as the page cache is
> also trying to grow. Afterwards we shrink the balloon back to zero (so
> total deflate = total inflate).
> Without patch (kernel 4.19.0-5):
> Inflation never reaches the target until we stop the "cat file >
> /dev/null" process. Total inflation time was 542 seconds. The longest
> period that made no net forward progress was 315 seconds (see attached
> graph).
> Result of "grep balloon /proc/vmstat" after the test:
> balloon_inflate 154828377
> balloon_deflate 154828377
> With patch (kernel 5.6.0-rc4+):
> Total inflation duration was 63 seconds. No deflate-queue activity
> occurs when pressuring the page-cache.
> Result of "grep balloon /proc/vmstat" after the test:
> balloon_inflate 12968539
> balloon_deflate 12968539
> Conclusion: This patch fixes the issue. In the test it reduced
> inflate/deflate activity by 12x, and reduced inflation time by 8.6x.
> But more importantly, if we hadn't killed the "grep balloon
> /proc/vmstat" process then, without the patch, the inflation process
> would never reach the target.
> Attached is a png of a graph showing the problematic behavior without
> this patch. It shows deflate-queue activity increasing linearly while
> balloon size stays constant over the course of more than 8 minutes of
> the test.

OK this is now queued for -next. Tyler thanks a lot for the detailed
test report - it's really awesome! I included it in the commit log in
full so that if we need to come back to this it's easy to reproduce the


 \ /
  Last update: 2020-03-09 11:24    [W:0.074 / U:6.180 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site