Messages in this thread |  | | From | Dieter Nützel <> | Subject | Re: [PATCH] Preemption Latency Measurement Tool | Date | Fri, 21 Sep 2001 00:51:48 +0200 |
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Am Freitag, 21. September 2001 00:03 schrieb Oliver Xymoron: > On Thu, 20 Sep 2001, Dieter Nützel wrote: > > Am Donnerstag, 20. September 2001 23:10 schrieb Robert Love: > > > On Thu, 2001-09-20 at 04:21, Andrea Arcangeli wrote: > > > > > You've forgotten a one liner. > > > > > > > > > > #include <linux/locks.h> > > > > > +#include <linux/compiler.h> > > > > > > > > woops, didn't trapped it because of gcc 3.0.2. thanks. > > > > > > > > > But this is not enough. Even with reniced artsd (-20). > > > > > Some shorter hiccups (0.5~1 sec). > > > > > > > > I'm not familiar with the output of the latency bench, but I actually > > > > read "4617" usec as the worst latency, that means 4msec, not 500/1000 > > > > msec. > > > > > > Right, the patch is returning the length preemption was unavailable > > > (which is when a lock is held) in us. So it is indded 4ms. > > > > > > But, I think Dieter is saying he _sees_ 0.5~1s latencies (in the form > > > of audio skips). This is despite the 4ms locks being held. > > > > Yes, that's the case. During dbench 16,32,40,48, etc... > > You might actually be waiting on disk I/O and not blocked. > > Does your audio source depend on any files (eg mp3s) and if so, could they > be moved to a ramfs? Do the skips go away then?
Good point.
I've copied one video (MP2) and one Ogg-Vorbis file into /dev/shm. Little bit better but hiccup still there :-(
dbench 16 Throughput 25.7613 MB/sec (NB=32.2016 MB/sec 257.613 MBit/sec) 7.500u 29.870s 1:22.99 45.0% 0+0k 0+0io 511pf+0w
Worst 20 latency times of 3298 measured in this period. usec cause mask start line/file address end line/file 11549 spin_lock 1 678/inode.c c01566d7 704/inode.c
c01566a0 T prune_icache c01566d7 ..... <<<<< c0156800 T shrink_icache_memory
7395 spin_lock 1 291/buffer.c c014151c 285/buffer.c
c0141400 T kupdate c014151c ..... <<<<< c0141610 T set_buffer_async_io
7372 spin_lock 1 291/buffer.c c01413e3 280/buffer.c
c0141290 T bdflush c01413e3 ..... <<<<< c0141400 T kupdate
5702 reacqBKL 1 1375/sched.c c0114d94 697/sched.c
c0114d60 T preempt_schedule c0114d94 ..... <<<<< c0114e10 T wake_up_process
4744 BKL 0 2763/buffer.c c01410aa 697/sched.c
c0141080 t sync_old_buffers c01410aa ..... <<<<< c01411b0 T block_sync_page
4695 spin_lock 1 291/buffer.c c014151c 280/buffer.c 4551 spin_lock 1 1376/sched.c c0114db3 1380/sched.c 4466 spin_lock 1 547/sched.c c0112fe4 1306/inode.c 4464 spin_lock 1 1376/sched.c c0114db3 697/sched.c 4146 reacqBKL 1 1375/sched.c c0114d94 842/inode.c 4131 spin_lock 0 547/sched.c c0112fe4 697/sched.c 3900 reacqBKL 1 1375/sched.c c0114d94 929/namei.c 3390 spin_lock 1 547/sched.c c0112fe4 1439/namei.c 3191 BKL 0 1302/inode.c c016f359 842/inode.c 2866 BKL 0 1302/inode.c c016f359 1381/sched.c 2803 reacqBKL 0 1375/sched.c c0114d94 1381/sched.c 2762 BKL 0 30/inode.c c016ce51 52/inode.c 2633 BKL 0 2763/buffer.c c01410aa 1380/sched.c 2629 BKL 0 2763/buffer.c c01410aa 1381/sched.c 2466 spin_lock 1 468/vmscan.c c0133c35 415/vmscan.c
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dbench 16 + renice artsd -20 works GREAT!
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dbench 32 and above + renice artsd -20 fail
Writing this during dbench 32 ...:-)))
dbench 32 + renice artsd -20 Throughput 18.5102 MB/sec (NB=23.1378 MB/sec 185.102 MBit/sec) 15.240u 63.070s 3:49.21 34.1% 0+0k 0+0io 911pf+0w
Worst 20 latency times of 3679 measured in this period. usec cause mask start line/file address end line/file 17625 spin_lock 1 678/inode.c c01566d7 704/inode.c
c01566a0 T prune_icache c01566d7 ..... <<<<< c0156800 T shrink_icache_memory
9829 spin_lock 1 547/sched.c c0112fe4 697/sched.c 9186 spin_lock 1 547/sched.c c0112fe4 1306/inode.c 7447 reacqBKL 1 1375/sched.c c0114d94 697/sched.c 7097 BKL 1 1302/inode.c c016f359 697/sched.c 5974 spin_lock 1 1376/sched.c c0114db3 697/sched.c 5231 BKL 1 1437/namei.c c014c42f 697/sched.c 5192 spin_lock 0 1376/sched.c c0114db3 1380/sched.c 4992 reacqBKL 1 1375/sched.c c0114d94 1381/sched.c 4875 spin_lock 1 305/dcache.c c0153acd 80/dcache.c 4390 BKL 1 927/namei.c c014b2bf 929/namei.c 3616 reacqBKL 0 1375/sched.c c0114d94 1306/inode.c 3498 spin_lock 1 547/sched.c c0112fe4 929/namei.c 3427 spin_lock 1 547/sched.c c0112fe4 842/inode.c 3323 BKL 1 1302/inode.c c016f359 1306/inode.c 3165 BKL 1 452/exit.c c011af61 697/sched.c 3059 spin_lock 1 305/dcache.c c0153acd 86/dcache.c 3016 BKL 1 533/inode.c c016d9cd 1306/inode.c 2943 BKL 1 1302/inode.c c016f359 52/inode.c 2904 spin_lock 1 547/sched.c c0112fe4 1439/namei.c
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