Messages in this thread | | | Date | Thu, 31 Jan 2013 09:25:49 -0700 | From | David Ahern <> | Subject | Re: [PATCH] perf script: Add a python script to statistic direct io behavior |
| |
Hi
On 1/31/13 2:08 AM, chenggang.qin@gmail.com wrote: > From: chenggang.qin@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
| |