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Date:      Mon, 12 Mar 2018 16:36:05 -0400
From:      Arshan Khanifar <arshan@freebsdfoundation.org>
To:        Slawa Olhovchenkov <slw@zxy.spb.ru>
Cc:        Ed Maste <emaste@freebsd.org>, FreeBSD Current <freebsd-current@freebsd.org>
Subject:   Re: Performance Benchmark for PTI (aka Meltdown mitigation)
Message-ID:  <CADMyxquwH2MtUz6=eLwnBqj82F8BfiAHTscKbk-A8z%2BdrSw__w@mail.gmail.com>
In-Reply-To: <20180309151606.GP81872@zxy.spb.ru>
References:  <CADMyxqs93mbwxJB4C03LMfz5g3T45=n9NWBet_Wa22v4BO4LLA@mail.gmail.com> <20180309120131.GA38546@zxy.spb.ru> <CAPyFy2D7GNv7g_=oBHGK0wPxxmY57NdnCirZXLxCnx9WggDxKQ@mail.gmail.com> <20180309151606.GP81872@zxy.spb.ru>

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I did some benchmarking for the two revisions:
results are here:
https://github.com/ArshanKhanifar/pti-benchmark/tree/master/stable-11-pre-after/results
first file is before pti patch and second file is after pti patch.

On Fri, Mar 9, 2018 at 10:16 AM, Slawa Olhovchenkov <slw@zxy.spb.ru> wrote:

> On Fri, Mar 09, 2018 at 09:58:55AM -0500, Ed Maste wrote:
>
> > On 9 March 2018 at 07:01, Slawa Olhovchenkov <slw@zxy.spb.ru> wrote:
> > > On Thu, Mar 08, 2018 at 05:04:11PM -0500, Arshan Khanifar wrote:
> > >
> > >> Executive Summary:
> > >> - The PTI feature increases the system call times by more than 100%.
> > >> - As a macrobenchmark, buildworld was used. Wall clock and user time
> > >> showed no statistically-significant changes, while system time
> > >> increased by less than 5%.
> > >>
> > >> This email contains the results for benchmarking the performance of
> the
> > >> PTI patch on FreeBSD 12-current. As a microbenchmark, timing of
> > >> getppid(2) system call was used, and as a macrobenchmark, a number of
> > >> buildworld tasks were timed.
> > >>
> > >
> > > Can you also run pre-patched kernel?
> >
> > It's not easy to do an apples-to-apples comparison as there were a few
> > followup changes to the PTI work, interspersed with unrelated changes.
> > That said, I think Arshan has some benchmarks obtained during the
> > development of the PTI changes that may be illustrative.
> >
> > The best approach is probably to compare stable/11 at r329450 (last
> > stable/11 revision before the merge) with r329462 with PTI and IBRS
> > disabled.
>
> Stable/11 more interesting to me, nice to see.
>
>



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