Fwd: Re: [PATCH v4] btrfs: Use larger zlib buffer for s390 hardware compression

[Zaslonko Mikhail]

Hello Andrew,

Could you please pick this V4 btrfs patch and the other five patches from V3 patch
set (https://lkml.org/lkml/2020/1/3/568).

Older patches can be dropped from linux-next:
 * ac2aeaa0f4d3 btrfs: use larger zlib buffer for s390 hardware compression
 * ac19f15aea33 lib/zlib: add zlib_deflate_dfltcc_enabled() function
 * 3447c9a51196 s390/boot: add dfltcc= kernel command line parameter
 * 890060df4401 lib/zlib: add s390 hardware support for kernel zlib_inflate
 * 148f7d060405 s390/boot: rename HEAP_SIZE due to name collision
 * bfbef17740fd lib/zlib: add s390 hardware support for kernel zlib_deflate

Thanks,
Mikhail.


-------- Forwarded Message --------
Subject: Re: [PATCH v4] btrfs: Use larger zlib buffer for s390 hardware compression
Date: Tue, 14 Jan 2020 17:18:57 +0100
From: David Sterba <dsterba@xxxxxxx>
Reply-To: dsterba@xxxxxxx
To: Mikhail Zaslonko <zaslonko@xxxxxxxxxxxxx>
CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Chris Mason <clm@xxxxxx>, Josef Bacik <josef@xxxxxxxxxxxxxx>, David Sterba <dsterba@xxxxxxxx>, Richard Purdie <rpurdie@xxxxxxxxx>, Heiko Carstens <heiko.carstens@xxxxxxxxxx>, Vasily Gorbik <gor@xxxxxxxxxxxxx>, Christian Borntraeger <borntraeger@xxxxxxxxxx>, Eduard Shishkin <edward6@xxxxxxxxxxxxx>, Ilya Leoshkevich <iii@xxxxxxxxxxxxx>, linux-s390@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx

On Wed, Jan 08, 2020 at 11:51:03AM +0100, Mikhail Zaslonko wrote:
> In order to benefit from s390 zlib hardware compression support,
> increase the btrfs zlib workspace buffer size from 1 to 4 pages (if
> s390 zlib hardware support is enabled on the machine). This brings up
> to 60% better performance in hardware on s390 compared to the PAGE_SIZE
> buffer and much more compared to the software zlib processing in btrfs.
> In case of memory pressure, fall back to a single page buffer during
> workspace allocation.
> The data compressed with larger input buffers will still conform to zlib
> standard and thus can be decompressed also on a systems that uses only
> PAGE_SIZE buffer for btrfs zlib.
> 
> Signed-off-by: Mikhail Zaslonko <zaslonko@xxxxxxxxxxxxx>

Reviewed-by: David Sterba <dsterba@xxxxxxxx>