Date: Sun, 29 Apr 2012 15:07:40 +0300 From: Alexander Motin <mav@FreeBSD.org> To: Oliver Pinter <oliver.pntr@gmail.com> Cc: Davide Italiano <davide@freebsd.org>, Albert Shih <Albert.Shih@obspm.fr>, Luigi Rizzo <rizzo@iet.unipi.it>, freebsd-stable@freebsd.org, Ian Smith <smithi@nimnet.asn.au> Subject: Re: High load event idl. Message-ID: <4F9D2F0C.4050501@FreeBSD.org> In-Reply-To: <CAPjTQNF=0Hgq_7BxeK_8o6DRQ%2BUJ_r94Y3PqwF8f_ccDeA_hHQ@mail.gmail.com> References: <20120427203013.GB60961@pcjas.obspm.fr> <CAPjTQNFsHZQLp8oMwhjkAWLnYZ5mPv9kr9=X5GhqHqExoHM0yw@mail.gmail.com> <20120427213459.GA61125@pcjas.obspm.fr> <4F9B946D.3030607@FreeBSD.org> <CAPjTQNGts290DyjORNfir8_rZ5S_vdog%2BJMEBA9mc2vJhUa=jg@mail.gmail.com> <4F9CCEF2.6050609@FreeBSD.org> <20120429155512.M91148@sola.nimnet.asn.au> <4F9CDE91.1060300@FreeBSD.org> <CAPjTQNF=0Hgq_7BxeK_8o6DRQ%2BUJ_r94Y3PqwF8f_ccDeA_hHQ@mail.gmail.com>
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On 04/29/12 15:04, Oliver Pinter wrote: > Removing dummynet from kernel don't chanage anything, that is releated > to load average. The loadavg hold to 0.70 +/- 0.2. (single user : sh + > top) New ktr dump? > On 4/29/12, Alexander Motin<mav@freebsd.org> wrote: >> On 04/29/12 09:09, Ian Smith wrote: >>> On Sun, 29 Apr 2012 08:17:38 +0300, Alexander Motin wrote: >>> > On 04/29/12 01:53, Oliver Pinter wrote: >>> > > Attached the ktr file. This is on core2duo P9400 cpu ( >>> > > smbios.system.product="HP ProBook 5310m (WD792EA#ABU)" ). The >>> workload >>> > > is only a single user boost: sh + top running, but the load >>> average is >>> > > near 0.5. >>> > >>> > ktr shows no real load there. But it shows that you are using >>> dummynet, that >>> > schedules its runs on every hardclock tick. I believe that load you >>> see is >>> > the result or synchronization between dummynet calls and loadvg >>> sampling, >>> > both of which called from hardclock. I think removing dummynet from >>> equation, >>> > should hide this problem and also reduce you laptops power >>> consumption. >>> > >>> > What's about fixing this, it is loadavg sampling algorithm that >>> should be >>> > changed. Fixing dummynet to not run on every hardclock tick would >>> also be >>> > great. >>> >>> Wading in out of my depth, and copying Luigi in case he misses it .. but >>> even back in the olden days when HZ defaulted to 100, one was advised to >>> use HZ>= 1000 for smooth dummynet traffic shaping dispatch scheduling. >>> >>> I wonder, with the newer clocks and timers, whether there is another >>> clock that could be used for dummynet scheduling, that would not have >>> this effect (even if largely cosmetic?) on load average calculation? >> >> First of all, the easiest solution would be to make dummynet to schedule >> callout not automatically, but on first queued packet. I believe that in >> case of laptop the queue should be empty most of time and the callout >> calls are completely useless there. Luigi promised to look on this once. >> >> What's about better precision/removing synchronization -- there is >> starting GSoC project now (by davide@) to rewrite callout(9) subsystem >> to use better precision allowed by new timer drivers. While now it is >> possible to get raw access to additional timer hardware available on >> some systems, I don't think it is a good idea. -- Alexander Motin
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