Date: Tue, 29 Apr 2014 20:57:00 +0400 From: Roman Bogorodskiy <novel@FreeBSD.org> To: Neel Natu <neelnatu@gmail.com> Cc: "freebsd-virtualization@freebsd.org" <freebsd-virtualization@freebsd.org> Subject: Re: [PATCH] Flexible vcpu pinning configuration Message-ID: <20140429165659.GB2170@kloomba> In-Reply-To: <CAFgRE9FUHEXbnkTSVmpyOP7EMzQh7QEFeNJikVWw6xHRWbvQSw@mail.gmail.com> References: <20140427104511.GA7804@kloomba> <CAFgRE9FUHEXbnkTSVmpyOP7EMzQh7QEFeNJikVWw6xHRWbvQSw@mail.gmail.com>
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Neel Natu wrote:
> Hi Roman,
>
> On Sun, Apr 27, 2014 at 3:45 AM, Roman Bogorodskiy <novel@freebsd.org> wrote:
> > I've created an initial version of the patch which allows more flexible
> > vcpu pinning configuration.
> >
> > Current schema is:
> >
> > bhyve -p N
> >
> > pins vcpu i to hostcpu N + i.
> >
> > The propsed extension is:
> >
> > bhyve -p N:M .... -p 0:1 -p 3:5
> >
> > which pins vcpu N to host pcpu M. Option needs to be specified
> > individually for each vcpu.
> >
> > So it works like that for me:
> >
> > sudo /usr/sbin/bhyve -p 0:0 -p 1:3 -c 2 ...
> >
> > # sudo cpuset -g -t 100262
> > tid 100262 mask: 0
> > # sudo cpuset -g -t 100264
> > tid 100264 mask: 3
> >
> > PS I used cpumat_t* array to store these values instead of int, because
> > if the idea is OK, I'll extend it to support ranges like e.g. cpuset(1)
> > supports, e.g.: "1:2-5".
> >
> > The questions are:
> >
> > - Is it OK to chance '-p' arg syntax or it's better to introduce a new
> > one?
> >
>
> I think we can reuse the "-p" option unless anybody objects vociferously.
>
> > - Is the syntax OK (currently: 'vcpu:pcpu', later
> > 'vcpu:pcpuN-pcpuM,pcpuX")?
>
> Yup, I think that works fine.
>
> The patch looks good in general but I have a few comments:
>
> - Scope of 'vcpupmap[]' should be restricted to 'static'.
>
> - usage() and man page need to be updated.
>
> - pincpu_parse():
> The option parsing can be made much easier by using:
>
> if (sscanf(str, "%d:%d", &vcpu, &pcpu) == 2) {
> /* success */
> } else {
> return (-1);
> }
>
> If the same vcpu is specified multiple times then we should
> malloc(sizeof(cpuset_t)) only the first time:
>
> if (vcpumap[vcpu] != NULL)
> mask = vcpumap[vcpu];
> else
> mask = malloc(sizeof(cpuset_t));
>
> We need to range-check 'vcpu' before using it as an index into the
> 'vcpumap[]' array.
Thanks for the comments, I'll make the fixes you pointed and re-send the
patch.
Roman Bogorodskiy
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