Date: Sun, 28 Aug 2016 16:30:12 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Adrian Chadd <adrian@freebsd.org> Cc: Bruce Simpson <bms@fastmail.net>, 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> Subject: Re: svn commit: r304436 - in head: . sys/netinet Message-ID: <20160828133012.GN88122@zxy.spb.ru> In-Reply-To: <CAJ-VmokC-8hW6uJaORLFQmb_nHdevHbVbBGVS3xGghs3jOKofg@mail.gmail.com> References: <20160826144926.GE88122@zxy.spb.ru> <3dba1b70-54cc-0bb1-5cc8-8c56cd750bec@fastmail.net> <20160826151324.GF88122@zxy.spb.ru> <CAJ-Vmomg6ejJdZessaUU3DF%2BV%2BsQd=hMZwo_pDYpa4XjoB_ZcA@mail.gmail.com> <20160826213613.GH88122@zxy.spb.ru> <CAJ-VmomRDdg5EUUiAHOyVBzitd8cZ8bPGCrU9btnveWeW-_85g@mail.gmail.com> <20160826220255.GI88122@zxy.spb.ru> <CAJ-VmomFuh07_vBi%2BzdNrPs3%2BDni1AtYh_VNKbnACydbCxr7gw@mail.gmail.com> <20160827004617.GJ88122@zxy.spb.ru> <CAJ-VmokC-8hW6uJaORLFQmb_nHdevHbVbBGVS3xGghs3jOKofg@mail.gmail.com>
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On Sat, Aug 27, 2016 at 07:05:01PM -0700, Adrian Chadd wrote: > On 26 August 2016 at 17:46, Slawa Olhovchenkov <slw@zxy.spb.ru> wrote: > > On Fri, Aug 26, 2016 at 04:55:34PM -0700, Adrian Chadd wrote: > > > >> Hi, > >> > >> I use the kernel lock profiling debugging, > > > > I am already have 100% utilise all CPU cores, I think this is drop > > performance? > > > >> but you can use dtrace to > >> get an idea: > >> > >> dtrace -n 'lockstat:::adaptive-block { @[stack()] = sum(arg1); }' > > > > How to interpret results (how to distinct lock contention from lock > > cost/overhead (LOCK CMPXCGQ is very expensive))? > > well, paste the results? :) OK, thanks! http://m.uploadedit.com/ba3s/1472390519813.txt > the lock is expensive because it's contended. :) As I am understund lock contended: 1. Multiple thread wait same lock. 2. Performance not scaled by adding CPU power As I understund lock expensive: Intel cache coherence protocol is expensive and take lock 800K per second take too much cpu/memory bandwidth w/o any contention. Memory latency at cache miss too. Adding mory CPU power (more cores, more GHz) take me performane boost. I am think my case is not lock contended. > >> (https://wiki.freebsd.org/DTrace/One-Liners) > >> > >> > >> > >> -adrian
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