Re: nfsd "serializing" patch

[yamt%mwd.biglobe.ne.jp@localhost (YAMAMOTO Takashi)]

hi,

> Hello,
> while working on nfs performance issues with overquota writes (which
> turned out to be a ffs issue), I came up with the attached patch.
> What this does it, for nfs over TCP, restrict a socket buffer processing
> to a single thread (right now, all pending requests are processed
> by all threads in parallel). This has two advantages:
> - if a single client sends lots of request (like writes comming from a
>   linux client), a single thread is busy and other threads will be
>   available to serve other client's requests quickly
> - by avoiding CPU cache sharing and lock contention at the vnode level
>   (if all requests are for the same vnode, which is the common case),
>   we get sighly better performances.
> 
> My testbed is a linux box with 2 Opteron 2431 (12 core total) and 32GB RAM
> writing over gigabit ethernet to a NetBSD server (dual
> Intel(R) Xeon(TM) CPU 3.00GHz, 4 hyperthread cores total) running nfsd -tun4.
> Without the patch, the server processes about 1230 writes per second,
> with this patch it processes about 1250 writes/s.
> 
> Comments ?

interesting.

but doesn't it have ill effects if the client has multiple indepenedent
activities on the mount point?

YAMAMOTO Takashi

> 
> -- 
> Manuel Bouyer <bouyer%antioche.eu.org@localhost>
>      NetBSD: 26 ans d'experience feront toujours la difference
> --