Date: Tue, 17 Jul 2007 11:57:30 -0700 (PDT) From: youshi10@u.washington.edu To: Jeff Roberson <jroberson@chesapeake.net> Cc: lveax <lveax.m@gmail.com>, current@freebsd.org, Claus Guttesen <kometen@gmail.com> Subject: Re: ULE/SCHED_SMP diff for 7.0, buildkernel & thanks. Message-ID: <Pine.LNX.4.43.0707171157300.17139@hymn01.u.washington.edu> In-Reply-To: <20070717114147.J92541@10.0.0.1>
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On Tue, 17 Jul 2007, Jeff Roberson wrote: > With regards to buildkernel times; I do not want to sacrafice performance on > other benchmarks to improve buildkernel. The problem is that 4BSD is as > agressive as possible at scheduling work on idle cores. This behavior that > helps one buildworld hurts on other, in my opinion, more important benchmarks. > > For example: http://people.freebsd.org/~jeff/sysbench.png > > ULE is 33% faster than SCHED_4BSD at this mysql test. This is a direct result > of prefering to idle to make more efficient scheduling decisions. ULE is also > faster at various networking benchmarks for similar reasons. > > I also believe that while the real time may be slower on buildworld the system > and user time will be smaller by a degree greater than the delta in real time. > This means that while you're building packages you have a little more cpu time > leftover to handle other tasks. Furthermore, as the number of cores goes up > things start to tip in favor of ULE although this is somewhat because it's > harder for even 4BSD to keep them busy due to disk bandwidth. > > Thanks everyone for testing. Can someone confirm that they have tested with > x86 rather than amd64? I will probably commit later today. > > Thanks, > Jeff > > On Tue, 17 Jul 2007, Claus Guttesen wrote: > >>> > sched_ule: >>> > >>> > -j 3 buildkernel: 13:23 >>> > -j 4 buildkernel: 12:38 >>> > -j 5 buildkernel: 12:41 >>> > -j 6 buildkernel: 12:47 >>> > >>> > sched_4bsd: >>> > -j 3 buildkernel: 11:43 >>> > -j 4 buildkernel: 12:02 >>> > >>> > So sched_ule seems to handle more processes slightly better than 4bsd >>> > albeit it does it slower. ule's sweet spot is -j 4 and 4bsd is -j 3. >>> > >>> >>> 4bsd vs ULE >>> >>> -j 3 buildkernel: 11:43 vs -j 3 buildkernel: 13:23 >>> >>> -j 4 buildkernel: 12:02 vs -j 4 buildkernel: 12:38 >>> >>> >>> ULE is always slower? >> >> In my case yes. >> >> -- >> regards >> Claus >> >> When lenity and cruelty play for a kingdom, >> the gentlest gamester is the soonest winner. >> >> Shakespeare I need to sync my kernel sources on my i386 desktop, but yeah I'll give it a round tonight. -Garrett
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