From: David Sterba <dsterba@suse.cz>
To: Zaslonko Mikhail <zaslonko@linux.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>,
David Sterba <dsterba@suse.com>,
linux-btrfs@vger.kernel.org,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Eduard Shishkin <edward6@linux.ibm.com>,
linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 6/6] btrfs: Use larger zlib buffer for s390 hardware compression
Date: Fri, 13 Dec 2019 18:35:27 +0100 [thread overview]
Message-ID: <20191213173526.GC3929@twin.jikos.cz> (raw)
In-Reply-To: <97b3a11d-2e52-c710-ee25-157e562eb3d0@linux.ibm.com>
On Fri, Dec 13, 2019 at 05:10:10PM +0100, Zaslonko Mikhail wrote:
> Hello,
>
> Could you please review the patch for btrfs below.
>
> Apart from falling back to 1 page, I have set the condition to allocate
> 4-pages zlib workspace buffer only if s390 Deflate-Conversion facility
> is installed and enabled. Thus, it will take effect on s390 architecture
> only.
>
> Currently in zlib_compress_pages() I always copy input pages to the workspace
> buffer prior to zlib_deflate call. Would that make sense, to pass the page
> itself, as before, based on the workspace buf_size (for 1-page buffer)?
Doesn't the copy back and forth kill the improvements brought by the
hw supported decompression?
> As for calling zlib_deflate with Z_FINISH flush parameter in a loop until
> Z_STREAM_END is returned, that comes in agreement with the zlib manual.
The concerns are about zlib stream that take 4 pages on input and on the
decompression side only 1 page is available for the output. Ie. as if
the filesystem was created on s390 with dflcc then opened on x86 host.
The zlib_deflate(Z_FINISH) happens on the compresission side.
next prev parent reply other threads:[~2019-12-13 20:39 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-09 15:29 [PATCH v2 0/6] S390 hardware compression support for kernel zlib Mikhail Zaslonko
2019-12-09 15:29 ` [PATCH v2 1/6] lib/zlib: Add s390 hardware support for kernel zlib_deflate Mikhail Zaslonko
2019-12-09 15:29 ` [PATCH v2 2/6] s390/boot: Rename HEAP_SIZE due to name collision Mikhail Zaslonko
2019-12-09 15:29 ` [PATCH v2 3/6] lib/zlib: Add s390 hardware support for kernel zlib_inflate Mikhail Zaslonko
2019-12-09 15:29 ` [PATCH v2 4/6] s390/boot: Add dfltcc= kernel command line parameter Mikhail Zaslonko
2019-12-09 15:29 ` [PATCH v2 5/6] lib/zlib: Add zlib_deflate_dfltcc_enabled() function Mikhail Zaslonko
2019-12-09 15:29 ` [PATCH v2 6/6] btrfs: Use larger zlib buffer for s390 hardware compression Mikhail Zaslonko
2019-12-13 16:10 ` Zaslonko Mikhail
2019-12-13 17:35 ` David Sterba [this message]
2019-12-16 16:31 ` Zaslonko Mikhail
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