linux-kernel - Re: Very slow header cache in mutt if the maildir is on ext3

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Message-ID: <20081217161722.GA28303@dose.home.local>
Date:	Wed, 17 Dec 2008 17:17:22 +0100
From:	Tino Keitel <tino.keitel@....de>
To:	linux-kernel@...r.kernel.org
Cc:	Theodore Tso <tytso@....edu>
Subject: Re: Very slow header cache in mutt if the maildir is on ext3

On Wed, Dec 17, 2008 at 07:32:04 -0500, Theodore Tso wrote:

[...]

> I just checked mutt 1.5.17 in Ubunty Hardy, and it sorts the inodes
> even if maildir_header_cache_verify is unset.  (It sorts it earlier if
> that option is set, but a little later in the function, if it wasn't
> sorted earlier, it sorts it then.)  Check for calls to maildir_sort()
> that use md_cmp_inode(); in my version of mutt, there are two such
> calls in mh.c:maildir_delayed_parsing().

I checked maildir_sort(), and it wasn't called with
maildir_header_cache_verify unset. In the source, it looks like this:

#if USE_HCACHE
    if (option(OPTHCACHEVERIFY))
    {
      DO_SORT();
      ret = stat(fn, &lastchanged);
    }

...

   if (ctx->magic == M_MH)
      data = mutt_hcache_fetch (hc, p->h->path, strlen);
    else
      data = mutt_hcache_fetch (hc, p->h->path + 3, &maildir_hcache_keylen);

...

#endif /* USE_HCACHE */

    DO_SORT();

So DO_SORT() is called _after_ reading the header cache if
maildir_header_cache_verify is unset, which is too late, because the
hard disk seeks to death if the cache is read with the unsorted inode
list.

Regards,
Tino
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