From mboxrd@z Thu Jan  1 00:00:00 1970
From: Hans Reiser <reiser@namesys.com>
Subject: Re: ReiserFS v3 choking when free space falls below 10%?
Date: Sat, 08 Jul 2006 17:01:59 -0700
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To: Jeff Mahoney <jeffm@suse.com>
Cc: Mike Benoit <ipso@snappymail.ca>, Jan Kara <jack@suse.cz>, =?UTF-8?B?SnVyZSBQZcSNYXI=?= <pegasus@nerv.eu.org>, reiserfs-list@namesys.com

So limit the number of iterations of rejecting windows that are too
small.  Say, 8.

Hans

Jeff Mahoney wrote:

>
> What's happening is that we keep finding windows that are too small,
> which results in a lot of wasted effort. The cycle goes like this:
>
> if (unfm && is_block_in_journal(s, bmap_n, *beg, beg))
>         continue;
> /* first zero bit found; we check next bits */
> for (end = *beg + 1;; end++) {
>         if (end >= *beg + max || end >= boundary
>             || reiserfs_test_le_bit(end, bi->bh->b_data)) {
>                 next = end;
>                 break;
>         }
>         /* finding the other end of zero bit window requires
>          * looking into journal structures (in
>          * case of searching for free blocks for unformatted nodes) */
>         if (unfm && is_block_in_journal(s, bmap_n, end, &next))
>                 break;
> }
>
> If the window is too small, we end up looping up to the top and try to
> find another one. Since the overwhelming majority of the windows are too
> small, we go through just about all the bitmaps without backing off the
> window size.
>
> -Jeff
>
> --
> Jeff Mahoney
> SUSE Labs