Page MenuHomeFreeBSD

Add a sysctl to toggle the use of the sockets LOWAT when calculating auto window growth
ClosedPublic

Authored by j-nitrology.com on May 31 2017, 9:52 PM.

Details

Summary

For applications that don't send as aggressively, this helps ensure we still grow the local window by taking its low watermark into account. By default, SO_SNDLOWAT is a negligable 1024. When this number is bumped up for efficiency on a large number of sessions, it starts to affect the ability for growth in the current code.

Test Plan

We have been running with this SO_SNDLOWAT modification at LLNW for a few years

Diff Detail

Repository
rS FreeBSD src repository
Lint
Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

j-nitrology.com added a comment.EditedMay 31 2017, 9:55 PM

It may be more proper for this to go into tflag, but the downsides there is then it won't apply to existing sessions and we consume more space (which is low with the current padding). Open to any opinions, as locally we just have it hard coded on in any case.

hiren accepted this revision as: hiren.Jun 20 2017, 6:12 PM

I know this has been in prod for quite some time and works. I don't want to engage in "best-practices" for this. :-) LGTM.

gnn accepted this revision.Jun 20 2017, 11:30 PM
This revision is now accepted and ready to land.Jun 20 2017, 11:30 PM
This revision was automatically updated to reflect the committed changes.