Messages in this thread | | | Date | Fri, 24 Apr 2015 07:58:48 -0600 | From | David Ahern <> | Subject | Re: [Question] How does perf still record the stack of a specified pid even when that process is interrupted and CPU is scheduled to other process |
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On 4/24/15 7:31 AM, Yunlong Song wrote: > Now we are profiling the performance of ext4 and f2fs on an eMMC card with iozone, > we find a case that ext4 is better than f2fs in random write under the test of > "iozone -s 262144 -r 64 -i 0 -i 2". We want to analyze the I/O delay of the two > file systems. We have got a conclusion that 1% of sys_write takes up 60% time of > the overall sys_write (262144/64=4096). We want to find out the call stack during > this specific 1% sys_write. Our idea is to record the stack in a certain time period > and since the specific 1% case takes up 60% time, the total number of records of its > stack should also takes up 60% of the total records, then we can recognize those stacks > and figure out what the I/O stack of f2fs is doing in the 1% case.
And to address this specific profiling problem have you tried:
perf trace record -- iozone ... perf trace -i perf.data -S
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