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Don't use MADV_RANDOM

Open sdodson opened this issue 7 months ago • 3 comments

In addition to the explicit documented behavior in posix_madvise(2) this call since Linux 6.4 also causes the kernel to aggressively free pages from the page cache by short circuiting the LRU second chance mechanism. The result is compaction events that took 900ms now take up to 20s and a system which generally operated with near zero major page faults sees 600 or more major faults per second during compaction events.

We've tested this change in older kernels and observed no negative impact in typical cloud instances.

Fixes https://github.com/etcd-io/bbolt/issues/939

sdodson avatar Apr 08 '25 19:04 sdodson

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k8s-ci-robot avatar Apr 08 '25 19:04 k8s-ci-robot

Hi @sdodson. Thanks for your PR.

I'm waiting for a etcd-io member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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k8s-ci-robot avatar Apr 08 '25 19:04 k8s-ci-robot

CC @dusk125

sdodson avatar Apr 08 '25 19:04 sdodson