Date: Mon, 17 Nov 2008 19:36:40 +0800 From: "Archimedes Gaviola" <archimedes.gaviola@gmail.com> To: "John Baldwin" <jhb@freebsd.org> Cc: freebsd-smp@freebsd.org Subject: Re: CPU affinity with ULE scheduler Message-ID: <42e3d810811170336rf0a0357sf32035e8bd1489e9@mail.gmail.com> In-Reply-To: <42e3d810811170311uddc77daj176bc285722a0c8@mail.gmail.com> References: <42e3d810811100033w172e90dbl209ecbab640cc24f@mail.gmail.com> <200811111216.37462.jhb@freebsd.org> <42e3d810811130355x3857bceap447e134b18eee04b@mail.gmail.com> <200811131128.55220.jhb@freebsd.org> <42e3d810811170311uddc77daj176bc285722a0c8@mail.gmail.com>
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On Mon, Nov 17, 2008 at 7:11 PM, Archimedes Gaviola <archimedes.gaviola@gmail.com> wrote: > On Fri, Nov 14, 2008 at 12:28 AM, John Baldwin <jhb@freebsd.org> wrote: >> On Thursday 13 November 2008 06:55:01 am Archimedes Gaviola wrote: >>> On Wed, Nov 12, 2008 at 1:16 AM, John Baldwin <jhb@freebsd.org> wrote: >>> > On Monday 10 November 2008 11:32:55 pm Archimedes Gaviola wrote: >>> >> On Tue, Nov 11, 2008 at 6:33 AM, John Baldwin <jhb@freebsd.org> wrote: >>> >> > On Monday 10 November 2008 03:33:23 am Archimedes Gaviola wrote: >>> >> >> To Whom It May Concerned: >>> >> >> >>> >> >> Can someone explain or share about ULE scheduler (latest version 2 if >>> >> >> I'm not mistaken) dealing with CPU affinity? Is there any existing >>> >> >> benchmarks on this with FreeBSD? Because I am currently using 4BSD >>> >> >> scheduler and as what I have observed especially on processing high >>> >> >> network load traffic on multiple CPU cores, only one CPU were being >>> >> >> stressed with network interrupt while the rests are mostly in idle >>> >> >> state. This is an AMD-64 (4x) dual-core IBM system with GigE Broadcom >>> >> >> network interface cards (bce0 and bce1). Below is the snapshot of the >>> >> >> case. >>> >> > >>> >> > Interrupts are routed to a single CPU. Since bce0 and bce1 are both on >>> > the >>> >> > same interrupt (irq 23), the CPU that interrupt is routed to is going >> to >>> > end >>> >> > up handling all the interrupts for bce0 and bce1. This not something >> ULE >>> > or >>> >> > 4BSD have any control over. >>> >> > >>> >> > -- >>> >> > John Baldwin >>> >> > >>> >> >>> >> Hi John, >>> >> >>> >> I'm sorry for the wrong snapshot. Here's the right one with my concern. >>> >> >>> >> PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND >>> >> 17 root 1 171 52 0K 16K CPU0 0 54:28 95.17% idle: >> cpu0 >>> >> 15 root 1 171 52 0K 16K CPU2 2 55:55 93.65% idle: >> cpu2 >>> >> 14 root 1 171 52 0K 16K CPU3 3 58:53 93.55% idle: >> cpu3 >>> >> 13 root 1 171 52 0K 16K RUN 4 59:14 82.47% idle: >> cpu4 >>> >> 12 root 1 171 52 0K 16K RUN 5 55:42 82.23% idle: >> cpu5 >>> >> 16 root 1 171 52 0K 16K CPU1 1 58:13 77.78% idle: >> cpu1 >>> >> 11 root 1 171 52 0K 16K CPU6 6 54:08 76.17% idle: >> cpu6 >>> >> 36 root 1 -68 -187 0K 16K WAIT 7 8:50 65.53% >>> >> irq23: bce0 bce1 >>> >> 10 root 1 171 52 0K 16K CPU7 7 48:19 29.79% idle: >> cpu7 >>> >> 43 root 1 171 52 0K 16K pgzero 2 0:35 1.51% >> pagezero >>> >> 1372 root 10 20 0 16716K 5764K kserel 6 58:42 0.00% kmd >>> >> 4488 root 1 96 0 30676K 4236K select 2 1:51 0.00% sshd >>> >> 18 root 1 -32 -151 0K 16K WAIT 0 1:14 0.00% swi4: >>> > clock s >>> >> 20 root 1 -44 -163 0K 16K WAIT 0 0:30 0.00% swi1: >> net >>> >> 218 root 1 96 0 3852K 1376K select 0 0:23 0.00% syslogd >>> >> 2171 root 1 96 0 30676K 4224K select 6 0:19 0.00% sshd >>> >> >>> >> Actually I was doing a network performance testing on this system with >>> >> FreeBSD-6.2 RELEASE using its default scheduler 4BSD and then I used a >>> >> tool to generate big amount of traffic around 600Mbps-700Mbps >>> >> traversing the FreeBSD system in bi-direction, meaning both network >>> >> interfaces are receiving traffic. What happened was, the CPU (cpu7) >>> >> that handles the (irq 23) on both interfaces consumed big amount of >>> >> CPU utilization around 65.53% in which it affects other running >>> >> applications and services like sshd and httpd. It's no longer >>> >> accessible when traffic is bombarded. With the current situation of my >>> >> FreeBSD system with only one CPU being stressed, I was thinking of >>> >> moving to FreeBSD-7.0 RELEASE with the ULE scheduler because I thought >>> >> my concern has something to do with the distributions of load on >>> >> multiple CPU cores handled by the scheduler especially at the network >>> >> level, processing network load. So, if it is more of interrupt >>> >> handling and not on the scheduler, is there a way we can optimize it? >>> >> Because if it still routed only to one CPU then for me it's still >>> >> inefficient. Who handles interrupt scheduling for bounding CPU in >>> >> order to prevent shared IRQ? Is there any improvements with >>> >> FreeBSD-7.0 with regards to interrupt handling? >>> > >>> > It depends. In all likelihood, the interrupts from bce0 and bce1 are both >>> > hardwired to the same interrupt pin and so they will always share the same >>> > ithread when using the legacy INTx interrupts. However, bce(4) parts do >>> > support MSI, and if you try a newer OS snap (6.3 or later) these devices >>> > should use MSI in which case each NIC would be assigned to a separate CPU. >> I >>> > would suggest trying 7.0 or a 7.1 release candidate and see if it does >>> > better. >>> > >>> > -- >>> > John Baldwin >>> > >>> >>> Hi John, >>> >>> I try 7.0 release and each network interface were already allocated >>> separately on different CPU. Here, MSI is already working. >>> >>> PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND >>> 12 root 1 171 ki31 0K 16K CPU6 6 123:55 100.00% idle: >> cpu6 >>> 15 root 1 171 ki31 0K 16K CPU3 3 123:54 100.00% idle: >> cpu3 >>> 14 root 1 171 ki31 0K 16K CPU4 4 123:26 100.00% idle: >> cpu4 >>> 16 root 1 171 ki31 0K 16K CPU2 2 123:15 100.00% idle: >> cpu2 >>> 17 root 1 171 ki31 0K 16K CPU1 1 123:15 100.00% idle: >> cpu1 >>> 37 root 1 -68 - 0K 16K CPU7 7 9:09 100.00% irq256: >> bce0 >>> 13 root 1 171 ki31 0K 16K CPU5 5 123:49 99.07% idle: cpu5 >>> 40 root 1 -68 - 0K 16K WAIT 0 4:40 51.17% irq257: >> bce1 >>> 18 root 1 171 ki31 0K 16K RUN 0 117:48 49.37% idle: cpu0 >>> 11 root 1 171 ki31 0K 16K RUN 7 115:25 0.00% idle: cpu7 >>> 19 root 1 -32 - 0K 16K WAIT 0 0:39 0.00% swi4: >> clock s >>> 14367 root 1 44 0 5176K 3104K select 2 0:01 0.00% dhcpd >>> 22 root 1 -16 - 0K 16K - 3 0:01 0.00% yarrow >>> 25 root 1 -24 - 0K 16K WAIT 0 0:00 0.00% swi6: >> Giant t >>> 11658 root 1 44 0 32936K 4540K select 1 0:00 0.00% sshd >>> 14224 root 1 44 0 32936K 4540K select 5 0:00 0.00% sshd >>> 41 root 1 -60 - 0K 16K WAIT 0 0:00 0.00% irq1: >> atkbd0 >>> 4 root 1 -8 - 0K 16K - 2 0:00 0.00% g_down >>> >>> The bce0 interface interrupt (irq256) gets stressed out which already >>> have 100% of CPU7 while CPU0 is around 51.17%. Any more >>> recommendations? Is there anything we can do about optimization with >>> MSI? >> >> Well, on 7.x you can try turning net.isr.direct off (sysctl). However, it >> seems you are hammering your bce0 interface. You might want to try using >> polling on bce0 and seeing if it keeps up with the traffic better. >> >> -- >> John Baldwin >> > > With net.isr.direct=0, my IBM system lessens CPU utilization per > interface (bce0 and bce1) but swi1:net increase its utilization. > Can you explained what's happening here? What does net.isr.direct do > with the decrease of CPU utilization on its interface? I really wanted > to know what happened internally during the packets being processed > and received by the interfaces then to the device interrupt up to the > software interrupt level because I am confused when enabling/disabling > net.isr.direct in sysctl. Is there a tool that can we used to trace > this process just to be able to know which part of the kernel internal > is doing the bottleneck especially when net.isr.direct=1? By the way > with device polling enabled, the system experienced packet errors and > the interface throughput is worst, so I avoid using it though. > > PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND > > 16 root 1 171 ki31 0K 16K CPU10 a 86:06 89.06% idle: cpu10 > 27 root 1 -44 - 0K 16K CPU1 1 34:37 82.67% swi1: net > 52 root 1 -68 - 0K 16K WAIT b 51:59 59.77% irq32: bce1 > 15 root 1 171 ki31 0K 16K RUN b 69:28 43.16% idle: cpu11 > 25 root 1 171 ki31 0K 16K RUN 1 115:35 24.27% idle: cpu1 > 51 root 1 -68 - 0K 16K CPU10 a 35:21 13.48% irq31: bce0 > > > Regards, > Archimedes > One more thing, I observed that when net.isr.direct=1, bce0 is using irq256 and bce1 is using irq257 while net.isr.direct=0, bce0 is now using irq31 and bce1 is using irq32. What makes it different?
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