Date: Fri, 9 Mar 2018 09:58:55 -0500 From: Ed Maste <emaste@freebsd.org> To: Slawa Olhovchenkov <slw@zxy.spb.ru> Cc: Arshan Khanifar <arshan@freebsdfoundation.org>, FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: Performance Benchmark for PTI (aka Meltdown mitigation) Message-ID: <CAPyFy2D7GNv7g_=oBHGK0wPxxmY57NdnCirZXLxCnx9WggDxKQ@mail.gmail.com> In-Reply-To: <20180309120131.GA38546@zxy.spb.ru> References: <CADMyxqs93mbwxJB4C03LMfz5g3T45=n9NWBet_Wa22v4BO4LLA@mail.gmail.com> <20180309120131.GA38546@zxy.spb.ru>
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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.
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