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Re: definitions for /proc/fs/xfs/stat

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: definitions for /proc/fs/xfs/stat
From: Nathan Scott <nathans@xxxxxxxxxx>
Date: Mon, 17 Jun 2013 01:41:50 -0400 (EDT)
Cc: Mark Seger <mjseger@xxxxxxxxx>, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20130617024603.GJ29338@dastard>
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Reply-to: Nathan Scott <nathans@xxxxxxxxxx>
Thread-index: Q1p7lG+kMMof1BcYnGo6WDqIlrk1mg==
Thread-topic: definitions for /proc/fs/xfs/stat
Hey Dave,

----- Original Message -----
> ...
> Must be an old version of RHEL6, because 6.4 doesn't do any IO at
> all, same as upstream. This test workload is purely a metadata only
> workload (no data is written) and so it all gets gathered up by
> delayed logging.

*nod* - RHEL6.3.

> > I think it is still possible, FWIW.  One could use python ctypes (as in
> > Marks test program) and achieve a page-aligned POSIX memalign,
> I wasn't aware you could get memalign() through python at all. I
> went looking for this exact solution a couple of month ago when
> these problems started to be reported and couldn't find anything
> ...

Yes, on reflection it doesn't jive too well with the way python wants
to do reads, in particular - os.read takes a file and a size, there's
no buffer exposed at the API level (for input).

It would need to be a separate python module to the core set I guess
(with a C component), and a slightly different API - or at least some
additional APIs which can take in an aligned buffer, rather than just
allocating one each time - but I believe it's still feasible.



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