Re: [PATCH] Preemption Latency Measurement Tool

David Lang
2001-09-20T02:33:38Z

also how useful is the latency info once swapping starts? if you have
something that gets swapped out it will have horrible latency and skew the
results (or at the very least you won't know if the problem is disk IO or
fixable problems)

David Lang

On Wed, 19 Sep 2001, safemode wrote:

> Date: Wed, 19 Sep 2001 22:23:21 -0400
> From: safemode <safemode@speakeasy.net>
> To: Ignacio Vazquez-Abrams <ignacio@openservices.net>,
> linux-kernel@vger.kernel.org
> Subject: Re: [PATCH] Preemption Latency Measurement Tool
>
> Is it possible to run the 20 worsst latency thing without having the pre-empt
> patch ? I'd like to see how things run without the preempt patch and which
> ones are the slowest. The last time i used the pre-empt patch i had worse
> audio performance than not. Perhaps that's because i use alsa.
>
>
>
> On Wednesday 19 September 2001 21:40, Ignacio Vazquez-Abrams wrote:
> > I'm posting this in the hope that someone will find it useful.
> >
> > Worst 20 latency times of 4647 measured in this period.
> > usec cause mask start line/file address end line/file
> > 35735 spin_lock 1 358/memory.c c012c74a 379/memory.c
> > 14003 spin_lock 1 341/vmscan.c c013977b 362/vmscan.c
> > 13701 spin_lock 1 1376/sched.c c0118ef9 697/sched.c
> > 12533 BKL 7 2689/buffer.c c0149acc 697/sched.c
> > 12459 spin_lock 7 547/sched.c c0116ca3 697/sched.c
> > 10479 spin_lock 1 703/vmscan.c c013a213 685/vmscan.c
> > 10443 spin_lock 1 669/inode.c c015e8dd 696/inode.c
> > 9163 reacqBKL 1 1375/sched.c c0118edb 1381/sched.c
> > 8727 BKL 9 164/inode.c c0171885 188/inode.c
> > 8066 usb-uhci d 76/softirq.c c0120cf2 119/softirq.c
> > 8041 BKL 9 130/attr.c c015fbd4 143/attr.c
> > 7982 spin_lock 8 547/sched.c c0116ca3 204/namei.c
> > 6920 reacqBKL 5 1375/sched.c c0118edb 697/sched.c
> > 6720 spin_lock 0 1376/sched.c c0118ef9 1380/sched.c
> > 6567 spin_lock 0 661/vmscan.c c013a0f2 764/vmscan.c
> > 6365 spin_lock 0 703/vmscan.c c013a213 764/vmscan.c
> > 5680 BKL 1 452/exit.c c011f6c6 697/sched.c
> > 5646 spin_lock 0 227/inode.c c015df35 696/inode.c
> > 5428 spin_lock 1 710/inode.c c015ea08 696/inode.c
> > 4933 spin_lock 0 547/sched.c c0116ca3 1380/sched.c
> >
> > This was taken after compiling several packages and running dbench a few
> > times.
> >
> > I also ran it previously while running 'while true ; do python -c
> > range\(3e7\) ; done', and the first line had minimum latencies of 10000,
> > going as high as about 96000 when swapping.
> >
> > This is on an Athlon 1050/100 Asus A7V (KT133) with PC133 CL2 SDRAM running
> > 2.4.9-ac12-preempt1.
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>