Date: Fri, 9 Mar 2018 18:16:06 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Ed Maste <emaste@freebsd.org> Cc: Arshan Khanifar <arshan@freebsdfoundation.org>, FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: Performance Benchmark for PTI (aka Meltdown mitigation) Message-ID: <20180309151606.GP81872@zxy.spb.ru> In-Reply-To: <CAPyFy2D7GNv7g_=oBHGK0wPxxmY57NdnCirZXLxCnx9WggDxKQ@mail.gmail.com> References: <CADMyxqs93mbwxJB4C03LMfz5g3T45=n9NWBet_Wa22v4BO4LLA@mail.gmail.com> <20180309120131.GA38546@zxy.spb.ru> <CAPyFy2D7GNv7g_=oBHGK0wPxxmY57NdnCirZXLxCnx9WggDxKQ@mail.gmail.com>
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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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