linux-kernel - RE: [PATCH v5 0/5] dirty_log_perf

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Date:   Mon, 17 Oct 2022 00:47:33 +0000
From:   "Wang, Wei W" <wei.w.wang@...el.com>
To:     "Christopherson,, Sean" <seanjc@...gle.com>,
        Vipin Sharma <vipinsh@...gle.com>
CC:     David Matlack <dmatlack@...gle.com>,
        "andrew.jones@...ux.dev" <andrew.jones@...ux.dev>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v5 0/5] dirty_log_perf_test vCPU pinning

On Saturday, October 15, 2022 3:03 AM, Sean Christopherson wrote:
> On Fri, Oct 14, 2022, Vipin Sharma wrote:
> > On Fri, Oct 14, 2022 at 9:55 AM David Matlack <dmatlack@...gle.com>
> wrote:
> > >
> > > On Fri, Oct 14, 2022 at 9:34 AM Sean Christopherson <seanjc@...gle.com>
> wrote:
> > > >
> > > > On Fri, Oct 14, 2022, Wang, Wei W wrote:
> > > > > Just curious why not re-using the existing tools (e.g. taskset) to do the
> pinning?
> > > >
> > > > IIUC, you're suggesting the test give tasks meaningful names so
> > > > that the user can do taskset on the appropriate tasks?  The goal
> > > > is to ensure vCPUs are pinned before they do any meaningful work.
> > > > I don't see how that can be accomplished with taskset without some
> > > > form of hook in the test to effectively pause the test until the user (or
> some run script) is ready to continue.
> > >
> > > A taskset approach would also be more difficult to incorporate into
> > > automated runs of dirty_log_perf_test.
> > >
> > > >
> > > > Pinning aside, naming the threads is a great idea!  That would
> > > > definitely help debug, e.g. if one vCPU gets stuck or is lagging behind.
> > >
> > > +1
> >
> > I also like the idea.
> >
> > Sean:
> > Do you want a v6 with the naming patch or you will be fine taking v5,
> > if there are no changes needed in v5, and I can send a separate patch
> > for naming?
> 
> Definitely separate, this is an orthogonal change and I don't think there will be
> any conflict.  If there is a conflict, it will be trivial to resolve.  But since Wei
> provided a more or less complete patch, let's let Wei post a formal patch
> (unless he doesn't want to).

Yeah, I'm glad to take care of this. There are other places (e.g. hardware_disable_test.c)
that seem good to have this as well, I'll cover them in one patchset.