Date: Fri, 26 Aug 2016 16:01:14 +0100 From: Bruce Simpson <bms@fastmail.net> To: Slawa Olhovchenkov <slw@zxy.spb.ru> Cc: Ryan Stone <rysto32@gmail.com>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, Ryan Stone <rstone@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, Adrian Chadd <adrian@freebsd.org> Subject: Re: svn commit: r304436 - in head: . sys/netinet Message-ID: <3dba1b70-54cc-0bb1-5cc8-8c56cd750bec@fastmail.net> In-Reply-To: <20160826144926.GE88122@zxy.spb.ru> References: <CAFMmRNx=2v=M8GCBQ_cN4pnuZ4VnyzncwAgsqMUE=ebz7pkp2A@mail.gmail.com> <20160820184506.GV8192@zxy.spb.ru> <CAFMmRNy-e1uzdtz2cb5DAa9kRd%2BkHg%2BmWbf=HNDWVdGGjOPUWA@mail.gmail.com> <eb4c228e-8efe-b519-e85b-87800b3ec7a1@fastmail.net> <0f42c5fb-f930-c6e3-75d6-df97f67c201d@fastmail.net> <20160820204106.GW8192@zxy.spb.ru> <0acba141-4701-d9c2-0ddb-46d1f60ff55b@fastmail.net> <20160820220510.GX8192@zxy.spb.ru> <8ac23bd1-dcb3-7c64-f195-5039f9af0eaf@fastmail.net> <20160821000400.GY8192@zxy.spb.ru> <20160826144926.GE88122@zxy.spb.ru>
next in thread | previous in thread | raw e-mail | index | archive | help
Slawa, I'm afraid this may be a bit of a non-sequitur. Sorry.. I seem to be missing something. As I understand it this thread is about Ryan's change to netinet for broadcast. On 26/08/16 15:49, Slawa Olhovchenkov wrote: > On Sun, Aug 21, 2016 at 03:04:00AM +0300, Slawa Olhovchenkov wrote: >> On Sun, Aug 21, 2016 at 12:25:46AM +0100, Bruce Simpson wrote: >>> Whilst I agree with your concerns about multipoint, I support the >>> motivation behind Ryan's original change: optimize the common case. >> >> Oh, common case... >> I am have pmc profiling for TCP output and see on this SVG picture and >> don't find any simple way. >> You want to watch too? > > At time peak network traffic (more then 25K connections, about 20Gbit > total traffic) half of cores fully utilised by network stack. > > This is flamegraph from one core: http://zxy.spb.ru/cpu10.svg > This is same, but stack cut of at ixgbe_rxeof for more unified > tcp/ip stack view http://zxy.spb.ru/cpu10u.svg ... I appreciate that you've taken the time to post a flamegraph (a fashionable visualization) of relative performance in the FreeBSD networking stack. Sadly, I am mostly out of my depth for looking at stack wide performance for the moment; for the things I look at involving FreeBSD at work just at the moment, I would not generally go down there except for specific performance issues (e.g. with IEEE 1588). It sounds as though perhaps you should raise a wider discussion about your results on -net. I would caution you however that the Function Boundary Trace (FBT) provider for DTrace can introduce a fair amount of noise to the raw performance data because of the trap mechanism it uses. This ruled it out for one of my own studies requiring packet-level accuracy. Whilst raw pmc(4) profiles may require more post-processing, they will provide less equivocal data (and a better fix) on the hot path, due also to being sampled effectively on a PMC interrupt (a gather stage- poll core+uncore MSRs), not purely a software timer interrupt. thanks Bruce
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?3dba1b70-54cc-0bb1-5cc8-8c56cd750bec>