New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

buffer, osd: add missing crc cache miss perf counter #14957

Merged
merged 1 commit into from May 10, 2017

Conversation

Projects
None yet
3 participants
@branch-predictor
Member

branch-predictor commented May 4, 2017

This helps tracking if/how effective is the CRC cache in bufferlists.

Signed-off-by: Piotr Dałek piotr.dalek@corp.ovh.com

@liewegas liewegas added the performance label May 4, 2017

@liewegas

This comment has been minimized.

Member

liewegas commented May 4, 2017

Have you tried running this on a test cluster? I'm worried about the overhead of the perf counter here. Ideally (in my mind) we can conclude from testing with this that the crc cache is ineffective and remove it entirely... :)

@branch-predictor

This comment has been minimized.

Member

branch-predictor commented May 4, 2017

I actually did and found results interesting. According to this, the effectiveness of crc cache is around 23% for filestore and 44% on bluestore (tested on vstart cluster with rados bench write/read 4m for 60s), i.e. 23%/44% of crc requests were cache hits (either direct or adjusted). I pushed out this pr so others can check that on their clusters.
Regarding performance, the cost of this PR for regular use case (without CEPH_BUFFER_TRACK env var set) would be as large as one branch, close to meaningless considering what else is done during destruction.

@liewegas

This comment has been minimized.

Member

liewegas commented May 5, 2017

please rebase!

buffer, osd: add missing crc cache miss perf counter
This helps tracking if/how effective is the CRC cache in bufferlists.

Signed-off-by: Piotr Dałek <piotr.dalek@corp.ovh.com>
@branch-predictor

This comment has been minimized.

Member

branch-predictor commented May 9, 2017

Rebased.

@tchaikov tchaikov added the needs-qa label May 9, 2017

@liewegas liewegas merged commit 99aeb52 into ceph:master May 10, 2017

3 checks passed

Signed-off-by all commits in this PR are signed
Details
Unmodifed Submodules submodules for project are unmodified
Details
default Build finished.
Details

@branch-predictor branch-predictor deleted the ovh:bp-crc-cache-miss-counter branch May 23, 2017

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment