Hi
On 1/31/13 2:08 AM, chenggang....@gmail.com wrote:
From: chenggang....@gmail.com
This patch depends on a prev patch: https://lkml.org/lkml/2013/1/29/47
If the engineers want to analyze the direct io behavior of some applications
without source code, perf tools with some appropriate tracepoints events in the
VFS subsystem are excellent choice.
Many database systems use their own page cache subsystems and use the direct IO
to access the disks. Sometimes, the system engineers need to know the misses
rate
of the database system's page cache. This requirements can be satisfied by
recording
the database's file access behavior through the way of direct IO. So, we use 2
tracepoint events to record the system wide's direct IO behavior. The 2
tracepoint
events are:
1) vfs:direct_io_read
2) vfs:direct_io_write
they were introduced by the patch: https://lkml.org/lkml/2013/1/29/47
The script direct-io.py are introduced by this patch can record the 2 tracepoint
events, analyse the sample data, and give a concise report.
What does this option provide that the I/O accounting with taskstats
(e.g., iotop) does not provide?
David
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