linux-ext4 - Re: [qrxd43@...orola.com: [PATCH V2] ext4: speed-up releasing blocks on commit]

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Message-ID: <CAA0+VHyOqK-yQqWZPjkwfTDzfFj_Bvy=cAtUdZXx1vOS6B7OcA@mail.gmail.com>
Date:	Wed, 13 Mar 2013 14:38:55 +0400
From:	Andrey Sidorov <qrxd43@...orola.com>
To:	Alex Tomas <bzzz.tomas@...il.com>
Cc:	Andreas Dilger <adilger@...ger.ca>, linux-ext4@...r.kernel.org
Subject: Re: [qrxd43@...orola.com: [PATCH V2] ext4: speed-up releasing blocks
 on commit]

Hi Alex,

Thanks for review! I'll post rebased patch with comments and some
ascii art this weekend.

> the patch looks fine, the only suggestion is to move the following logic
> into mb_buddy_mark_free():
>
> + if (first & 1) {
> + first += !left_is_free;
> + e4b->bd_info->bb_counters[0] += left_is_free ? -1 : 1;
> + }
> + if (!(last & 1)) {
> + last -= !right_is_free;
> + e4b->bd_info->bb_counters[0] += right_is_free ? -1 : 1;
> + }

I didn't do that since buddy[0] is a special case since it is in fact
bd_bitmap itself. Moving that into mb_buddy_mark_free will make code
look worse because of this special handling. I think unrolling first
iteration that handles bd_bitmap looks much better.

Regards,
Andrey.
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