On Wed, Nov 30, 2011 at 01:57:43AM +0800, Andi Kleen wrote:
> On Tue, Nov 29, 2011 at 09:09:03PM +0800, Wu Fengguang wrote:
> > Record the readahead pattern in ra->pattern and extend the ra_submit()
> > parameters, to be used by the next readahead tracing/stats patches.
>
> I like this, could it be exported it a bit more formally in /proc for
> each file descriptor?
Something like this?
$ cat /proc/self/fdinfo/2
pos: 0
flags: 0100002
+ ra_pattern: initial
+ ra_size: 4
It may be some rapidly changing information, however in practical
should remain stable unless it's changing access pattern a lot.
> I could imagine a monitoring tool that you run on a process that
> tells you what pattern state the various file descriptors are in and how
> large the window is. That would be similar to the tools for
> monitoring network connections, which are extremly useful
> in practice.
Yeah, the simplest form may be
watch "head /proc/self/fdinfo/*"
Thanks,
Fengguang
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