I recorded a 3 minutes of heavy IO (generated with fio) with:
blktrace -w 240 -a read -a write -a fs -I devs -o btrfs-12-blk.log
(I used 240 seconds to make sure I didn't miss any of the 180 seconds of
I/O).
As a small aside I wasn't sure what the default filter mask was, it
seems more correct to use:
blktrace -w 240 -A read -a write -a fs -I devs -o btrfs-12-blk.log
So set the mask to exactly (and only) read, then add write, and fs. But
that dies with:
Invalid set action mask read/0x0
The above mentioned file "devs" contains /etc/sdc1 ... /dev/sdn1 (12
devices, one per line).
It generated 16 log files (it's a dual socket x quad core/8 thread intel
CPUs). The logs total 15M (using du --total -h *blktrace*).
blkparse reliably seg faults at around 102 seconds into the log:
8,209 1 5749 102.246254903 4825 U N [(null)] 2
8,113 4 10445 102.255427790 0 C R 14356151 + 8 [10445]
Segmentation fault
Stderror does have some strange output:
# blkparse btrfs-12-blk.log > /dev/null
Bad magic 0
Bad magic 0
Bad magic 0
Bad magic 8
Bad magic 0
Bad magic 0
Bad magic 0
Bad magic c2d3ccfa
Segmentation fault
It generated 61,758 lines of output when it dies.
Additional information about this machine, it's an ubuntu 11.04 x86-64
machine with:
# uname -a
Linux fb 2.6.38-8-server #42-Ubuntu SMP Mon Apr 11 03:49:04 UTC 2011
x86_64 x86_64 x86_64 GNU/Linux
# blkparse --version
blkparse version 1.0.1
# blktrace --version
blktrace version 2.0.0
This doesn't seem like a particularly challenging log to handle.
I looked for a way to tell blkparse to use a larger buffer but I didn't
see a way to do that with blkparse --help or the blkparse man page.
Stupid user error? Suggestions? I'm sending it to this list as
directed by the man page.
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