Date: Wed, 27 May 2015 09:53:13 -0400 From: Kurt Lidl <lidl@pix.net> To: Bruce Evans <brde@optusnet.com.au>, Eitan Adler <eadler@freebsd.org> Cc: Adrian Chadd <adrian@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org> Subject: Re: svn commit: r281103 - head/sys/amd64/amd64 Message-ID: <5565CC49.1020800@pix.net> In-Reply-To: <20150406152653.K1066@besplex.bde.org> References: <201504050518.t355IFVJ001786@svn.freebsd.org> <20150405163305.A2515@besplex.bde.org> <CAF6rxgkZA=GbyQFhQC63c9z%2By_ki%2Byjt6fZW%2BP9cHve5L=pYoA@mail.gmail.com> <20150406152653.K1066@besplex.bde.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On 4/6/15 1:42 AM, Bruce Evans wrote: > On Mon, 6 Apr 2015, Eitan Adler wrote: > >> + a few people interested in the diff >> >> On 5 April 2015 at 02:55, Bruce Evans <brde@optusnet.com.au> wrote: >>> On Sun, 5 Apr 2015, Eitan Adler wrote: >> >> I did not confirm the performance impact, but the submitter and others >> indicated they saw a difference. >> >> Do you have specific data that shows that there was an improvement? > > Only micro-benchmark output that indicates little difference. This > is probably very MD (depending on write combining hardware), so you > might only see a difference on some systems. > > I also have micro-benchmark output for network packets/second that > shows 10% differences for the change of adding 1 byte of padding > in code that is never executed. This seems to be due to different > cache misses. To eliminate differences from this (except ones > caused by actually running different code), create a reference > version by padding the functions or data to be changed so that > the change doesn't affect the address of anything except the > internals of the changed parts. > > I might try a makeworld run to see if changing the non-temporal > accesses in pagecopy and pagezero to cached. I ran a few (total of 12) buildworld runs after this discussion. I finally got around to posting the results to the original bug. The data is here: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=199151#c3 -Kurt
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?5565CC49.1020800>