BBlack has submitted this change and it was merged.
Change subject: r::c::perf: disable autocorking
......................................................................
r::c::perf: disable autocorking
Change-Id: I96a2504dc1a6e53c1eed880a7a50dd94591581e7
---
M modules/role/manifests/cache/perf.pp
1 file changed, 13 insertions(+), 0 deletions(-)
Approvals:
BBlack: Looks good to me, approved
jenkins-bot: Verified
diff --git a/modules/role/manifests/cache/perf.pp
b/modules/role/manifests/cache/perf.pp
index 4d6e622..d039d8e 100644
--- a/modules/role/manifests/cache/perf.pp
+++ b/modules/role/manifests/cache/perf.pp
@@ -147,6 +147,19 @@
'net.ipv4.tcp_synack_retries' => 2,
'net.ipv4.tcp_syn_retries' => 2,
+ # TCP autocorking exists and defaults on from 3.14 onwards. The
+ # idea is that some applications that should be doing a better job
+ # of local buffering or manual TCP_CORK aren't, and the kernel
+ # detects the common patterns for this and auto-corks for them
+ # (doesn't immediately send a small write, instead waits a bit to
+ # see if it can coalesce it with another). Netstat counters for
+ # autocorking are running up at a huge rate (ballpark near our reqs
+ # or SYNs rate), which implies this is happening commonly to nginx
+ # outbound traffic. My theory is this is probably a net loss and
+ # nginx and/or openssl know what they're doing and we'd benefit
from
+ # the writes going out immediately and not autocorking...
+ 'net.ipv4.tcp_autocorking' => 0,
+
# Pure perf hacks (documented above)
'net.ipv4.tcp_notsent_lowat' => 131072,
'net.ipv4.tcp_slow_start_after_idle' => 0,
--
To view, visit https://gerrit.wikimedia.org/r/295588
To unsubscribe, visit https://gerrit.wikimedia.org/r/settings
Gerrit-MessageType: merged
Gerrit-Change-Id: I96a2504dc1a6e53c1eed880a7a50dd94591581e7
Gerrit-PatchSet: 1
Gerrit-Project: operations/puppet
Gerrit-Branch: production
Gerrit-Owner: BBlack <bbl...@wikimedia.org>
Gerrit-Reviewer: BBlack <bbl...@wikimedia.org>
Gerrit-Reviewer: jenkins-bot <>
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