Re: [PATCH] Preemption Latency Measurement Tool

safemode (safemode@speakeasy.net)
Wed, 19 Sep 2001 22:23:21 -0400


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.
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