From: Zaslonko Mikhail <zaslonko@linux.ibm.com>
To: Josef Bacik <josef@toxicpanda.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Chris Mason <clm@fb.com>, David Sterba <dsterba@suse.com>,
Richard Purdie <rpurdie@rpsys.net>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/5] btrfs: Increase buffer size for zlib functions
Date: Wed, 27 Nov 2019 14:42:20 +0100 [thread overview]
Message-ID: <11377b99-b66c-fdc3-5c8f-0bae34c92c03@linux.ibm.com> (raw)
In-Reply-To: <20191126155249.j2dktiggykfoz4iz@MacBook-Pro-91.local>
Hello,
On 26.11.2019 16:52, Josef Bacik wrote:
> On Tue, Nov 26, 2019 at 03:41:30PM +0100, Mikhail Zaslonko wrote:
>> Due to the small size of zlib buffer (1 page) set in btrfs code, s390
>> hardware compression is rather limited in terms of performance. Increasing
>> the buffer size to 4 pages would bring significant benefit for s390
>> hardware compression (up to 60% better performance compared to the
>> PAGE_SIZE buffer) and should not bring much overhead in terms of memory
>> consumption due to order 2 allocations.
>>
>> Signed-off-by: Mikhail Zaslonko <zaslonko@linux.ibm.com>
>
> We may have to make these allocations under memory pressure in the IO context,
> order 2 allocations here is going to be not awesome. If you really want it then
> you need to at least be able to fall back to single page if you fail to get the
> allocation. Thanks,
>
As far as I understand GFP_KERNEL allocations would never fail for the order <=
PAGE_ALLOC_COSTLY_ORDER. How else can the memory pressure condition be identified
here?
> josef
>
next prev parent reply other threads:[~2019-11-27 13:43 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-26 14:41 [PATCH 0/5] S390 hardware compression support for kernel zlib Mikhail Zaslonko
2019-11-26 14:41 ` [PATCH 1/5] lib/zlib: Add s390 hardware support for kernel zlib_deflate Mikhail Zaslonko
2019-11-26 14:41 ` [PATCH 2/5] s390/boot: Rename HEAP_SIZE due to name collision Mikhail Zaslonko
2019-11-26 14:41 ` [PATCH 3/5] lib/zlib: Add s390 hardware support for kernel zlib_inflate Mikhail Zaslonko
2019-11-26 14:41 ` [PATCH 4/5] s390/boot: Add dfltcc= kernel command line parameter Mikhail Zaslonko
2019-11-26 14:41 ` [PATCH 5/5] btrfs: Increase buffer size for zlib functions Mikhail Zaslonko
2019-11-26 15:52 ` Josef Bacik
2019-11-27 12:14 ` David Sterba
2019-11-27 13:54 ` Josef Bacik
2019-12-09 16:39 ` Zaslonko Mikhail
2019-11-27 13:42 ` Zaslonko Mikhail [this message]
2019-11-27 13:50 ` Josef Bacik
2019-11-27 13:54 ` David Sterba
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