Re: [PATCH 3/3] ext4: Find desired extent in ext4_ext_shift_extents() using binsearch

From: Roman Penyaev
Date: Fri Jan 06 2017 - 15:21:44 EST


On Thu, Jan 5, 2017 at 12:58 AM, Theodore Ts'o <tytso@xxxxxxx> wrote:
> It looks like the original (before your patch) 1k failures due to a
> bug introduced via the block.git tree, which has since been fixed in
> Linus's mainline tree as of today. It wouldn't surprise me if the bug
> interacted poorly your changes, so things will probably better with
> your patches applied directly on top of the tip of Linus's tree.
>
> That being said, it looks like there were still regressions introduced
> on the 4k configuration, so I'm in the middle of rerunning my baseline
> and trying out your patches as well.

I found a bug in my third patch, where I try to optimize linear search.
I missed the fact, that ext4_ext_binsearch() searches for the closest
extent from the left, but this linear search code does search for closest
extent from the right.

I ran the 'kvm-xfstests.sh -c 4k -g auto' against b25ead75e7b6 4.10-rc2
with and without my changes. No failures.

1k configuration was run against latest Linus's mainline. Also no
regressions were found: these two "generic/270, generic/273" fail
regardless my changes.

I will resend the patchset without latest patch shortly.

--
Roman