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>
next in thread | previous in thread | raw e-mail | index | archive | help
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
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20160828133012.GN88122>