--- On Wed, 1/9/13, Barney Cordoba <barney_cord...@yahoo.com> wrote:
> From: Barney Cordoba <barney_cord...@yahoo.com> > Subject: Re: To SMP or not to SMP > To: "Mark Atkinson" <atkin...@gmail.com> > Cc: freebsd-net@freebsd.org > Date: Wednesday, January 9, 2013, 1:08 PM > > > --- On Tue, 1/8/13, Mark Atkinson <atkin...@gmail.com> > wrote: > > > From: Mark Atkinson <atkin...@gmail.com> > > Subject: Re: To SMP or not to SMP > > To: freebsd-net@freebsd.org > > Date: Tuesday, January 8, 2013, 11:29 AM > > -----BEGIN PGP SIGNED MESSAGE----- > > Hash: SHA1 > > > > On 01/07/2013 18:25, Barney Cordoba wrote: > > > I have a situation where I have to run 9.1 on an > old > > single core > > > box. Does anyone have a handle on whether it's > better > > to build a > > > non SMP kernel or to just use a standard SMP build > with > > just the > > > one core? Thanks. > > > > You can build a SMP kernel, but you'll get better > > performance (in my > > experience) with SCHED_4BSD on single cpu than with > ULE. > > > > I've tested the 2 schedulers on an SMP kernel with 1 core. I > don't have > a 1 core system to test with so I'm using an E5520 > with 1 core enabled. > > Bridging a controlled test (curl-loader doing a web-load > test with 100 > users that consistently generates 870Mb/s and 77Kpps, I see > the following: > > top -SH > > ULE: > > idle: 74.85% > kernel {em1 que} 17.68% > kernel {em0 que} 5.86% > httpd: .49% > > 4BSD: > > idle: 70.95% > kernel {em1 que} 18.07% > kernel {em0 que} 4.44% > httpd: .93% > > Note that the https is a monitor I'm running. > > so it appears that theres 7% of usage missing (all other > apps show 0% > usage). > > If i had to guess just looking at the numbers, it seems that > 4BSD might > do better with the interrupt level stuff, and not as good > with user > level context switching. I think they're close enough to > stick with ULE > so I can just use a stock kernel. > > One thing that bothers me is the idle sits at 100% when > other tasks are > registering values under light loads, so it's certainly not > all that > accurate. > > BC Ok, thanks to J Baldwin's tip I got a NON-SMP kernel running with some interesting results. Here's all 4 tests: I've tested the 2 schedulers on an SMP kernel with 1 core. I don't have a 1 core system to test with so I'm using an E5520 with 1 core enabled. Bridging a controlled test (curl-loader doing a web-load test with 100 users that consistently generates 870Mb/s and 77Kpps, I see the following: top -SH ULE (SMP): idle: 74.85% kernel {em1 que} 17.68% kernel {em0 que} 5.86% httpd: .49% 4BSD (SMP): idle: 70.95% kernel {em1 que} 18.07% kernel {em0 que} 4.44% httpd: .93% 4BSD (NON-SMP): idle: 72.95% kernel {em1 que} 15.04% kernel {em0 que} 6.10% httpd: 1.17% ULE (NON-SMP): idle: 76.17% kernel {em1 que} 16.99% kernel {em0 que} 5.18% httpd: 1.66% A kernel with SMP off seems to be a bit more efficient. A better test would be to have more stuff running, but Im about out of time on this project. BC _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"