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Date:      Wed, 30 Dec 2015 10:22:07 -0800
From:      Hubbard Jordan <jkh@ixsystems.com>
To:        Niels de Vos <ndevos@redhat.com>
Cc:        Rick Macklem <rmacklem@uoguelph.ca>, freebsd-fs <freebsd-fs@freebsd.org>, gluster-devel@gluster.org
Subject:   Re: [Gluster-devel] FreeBSD port of GlusterFS racks up a lot of CPU usage
Message-ID:  <2D8C2729-D556-479B-B4E2-66E1BB222F41@ixsystems.com>
In-Reply-To: <20151230103152.GS13942@ndevos-x240.usersys.redhat.com>
References:  <571237035.145690509.1451437960464.JavaMail.zimbra@uoguelph.ca> <20151230103152.GS13942@ndevos-x240.usersys.redhat.com>

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> On Dec 30, 2015, at 2:31 AM, Niels de Vos <ndevos@redhat.com> wrote:
>=20
>> I'm guessing that Linux uses the event-epoll stuff instead of =
event-poll,
>> so it wouldn't exhibit this. Is that correct?
>=20
> Well, both. most (if not all) Linux builds will use event-poll. But,
> that calls epoll_wait() with a timeout of 1 millisecond as well.
>=20
>> Thanks for any information on this, rick
>> ps: I am tempted to just crank the timeout of 1msec up to 10 or =
20msec.
>=20
> Yes, that is probably what I would do too. And have both poll =
functions
> use the same timeout, have it defined in libglusterfs/src/event.h. We
> could make it a configurable option too, but I do not think it is very
> useful to have.

I guess this begs the question - what=E2=80=99s the actual purpose of =
polling for an event with a 1 millisecond timeout?  If it was some sort =
of heartbeat check, one might imagine that would be better served by a =
timer with nothing close to 1 millisecond as an interval (that would be =
one seriously aggressive heartbeat) and if filesystem events are =
incoming that glusterfs needs to respond to, why timeout at all?

I also have a broader question to go with the specific one:  We (at =
iXsystems) were attempting to engage with some of the Red Hat folks back =
when the FreeBSD port was first done, in the hope of getting it more =
=E2=80=9Cofficially supported=E2=80=9D for FreeBSD and perhaps even =
donating some more serious stress-testing and integration work for it, =
but when those Red Hat folks moved on we lost continuity and the effort =
stalled.  Who at Red Hat would / could we work with in getting this back =
on track?  We=E2=80=99d like to integrate glusterfs with FreeNAS 10, and =
in fact have already done so but it=E2=80=99s still early days and =
we=E2=80=99re not even really sure what we have yet.

Thanks,

- Jordan




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