smbd: High CPU usage
jra at samba.org
Thu Jul 19 16:02:30 UTC 2018
On Thu, Jul 19, 2018 at 07:32:13AM +0200, Volker Lendecke via samba-technical wrote:
> On Wed, Jul 18, 2018 at 04:16:46PM -0700, Jeremy Allison via samba-technical wrote:
> > On Wed, Jul 18, 2018 at 09:20:10PM +0300, Vadim Lazovskiy via samba-technical wrote:
> > > I would not agree.
> > > sendfile is great. It makes you able to serve content directly from disk to
> > > network without unnessesery copying to userspace. It saves you lots
> > > syscalls and context switching.
> > > As for our workload profile (1-2Gbit per server) it really saves CPU time.
> > >
> > > If someone of samba developers treat this as bug and eager to fix it I
> > > could provide extra information and do some debugging.
> > Here is a full patchset that should handle all platforms
> > for which we support sendfile(). Can you try it out and confirm it
> > fixes your issue ?
> I know syscalls are cheap, but don't the additional fcntl ones kill
> the performance advantage somewhat? We had discussions with a
> MIPS-based vendor in the past. On that platform (don't remember the
> exact OS version), syscalls were pretty expensive.
If you want performance, use a pthreadpool :-).
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