Re: [PATCH 3/3] Avoid doing extra 'lstat()'s for d_type if we have an up-to-date cache entry

From: Eric Blake <ebb9@byu.net>
Date: Jul 9, 2009, 21:52 UTC
Message-ID: <loom.20090709T214734-78@post.gmane.org>
In-Reply-To: <20090709210513.GB19425@dpotapov.dyndns.org>

Dmitry Potapov <dpotapov <at> gmail.com> writes:

Show 6 quoted lines

> With this patch, I see one 'stat' less for each directory, which on my
> repo resulted in about 10.7% less 'stat' or 4.8% less of the total
> number of syscalls. The total run time decreased by 4.6%.
> 
> Still, there are many stats for directories -- for each directory I see
> 2 + number of subdirectories it has, but I am not sure about its cause.

That would probably be the fact that in cygwin 1.5, a stat() of a directory results in querying all the contents of the directory so as to correctly populate the st_link member based on the number of subdirectories. In cygwin 1.7, in addition to adding the d_type member to readdir, stat was also changed to blindly return st_link of 1 for all directories rather than wasting time populating the st_link member (since Windows provides no efficient way of accessing that number).

-- 
Eric Blake