From: Dave Rodgman <dave.rodgman@arm.com>
To: "Markus F.X.J. Oberhumer" <markus@oberhumer.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>
Cc: "herbert@gondor.apana.org.au" <herbert@gondor.apana.org.au>,
"davem@davemloft.net" <davem@davemloft.net>,
Matt Sealey <Matt.Sealey@arm.com>,
"nitingupta910@gmail.com" <nitingupta910@gmail.com>,
"minchan@kernel.org" <minchan@kernel.org>,
"sergey.senozhatsky.work@gmail.com"
<sergey.senozhatsky.work@gmail.com>,
"sonnyrao@google.com" <sonnyrao@google.com>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
nd <nd@arm.com>, "sfr@canb.auug.org.au" <sfr@canb.auug.org.au>
Subject: Re: [PATCH v4 0/7] lib/lzo: performance improvements
Date: Fri, 7 Dec 2018 15:54:07 +0000 [thread overview]
Message-ID: <fba24452-ae3a-0caa-11b4-aea69abf2fff@arm.com> (raw)
In-Reply-To: <5C09448C.8010506@oberhumer.com>
Hi Markus,
On 06/12/2018 3:47 pm, Markus F.X.J. Oberhumer wrote:> Request 3 - add lzo-rle; *NOT* acked by me
>
> [PATCH 6/8] lib/lzo: implement run-length encoding
> [PATCH 7/8] lib/lzo: separate lzo-rle from lzo
> [PATCH 8/8] zram: default to lzo-rle instead of lzo
>
> It (1) silently changes the compressed data format
I'm not sure this is relevant: as a separate algorithm, there's no reason
to retain the same format (although backwards compatibility can help with
migration). If you know of a way to improve the compatibility aspect
though, that would be great!
> (2) crashes on MIPS,
Please could you provide more detail? I tested on x86-32, x86-64, arm,
arm64 and big-endian MIPS64, but if there is an issue I missed I'd like to
address it.
> and (3) makes compression and decompression on typical data 10% slower on
> X86_64 with our internal benchmarks,
It is of course data-dependent. In my testing, as I mentioned previously, RLE
without the other patches does regress slightly on high-entropy data, but
offers a win on low-entropy data. For the right applications (e.g., zram),
this makes it overall beneficial.
> and (4) has to be carefully checked for buffer overflows.
This has been reviewed prior to sharing on LKML, and of course tested,
but further review is of course welcome.
> As a final comment, I question the quality your benchmarks - combining
> arch-related ARM64 improvements and algorithmic changes into one
> benchmark comparision is just unprofessional marketing.
I felt it was helpful to show overall performance with the complete patchset:
this is what end-users experience. However, as you can see below, I also
previously shared a summary of the two main components of the patchset to
try and address this sort of concern:
>> As a quick summary of the impact of these patches on bigger chunks of
>> data, I've compared the performance of four different variants of lzo
>> on two large (~40 MB) files. The numbers show round-trip throughput
>> in MB/s:
>>
>> Variant | Low-entropy | High-entropy
>> Current lzo | 242 | 157
>> Arm opts | 290 | 159
>> RLE | 876 | 151
>> Arm opts + RLE | 1150 | 181
cheers
Dave
next prev parent reply other threads:[~2018-12-07 15:54 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-30 14:26 [PATCH v4 0/7] lib/lzo: performance improvements Dave Rodgman
2018-11-30 14:26 ` [PATCH 1/8] lib/lzo: tidy-up ifdefs Dave Rodgman
2018-12-06 15:49 ` Markus F.X.J. Oberhumer
2018-11-30 14:26 ` [PATCH 2/8] lib/lzo: clean-up by introducing COPY16 Dave Rodgman
2018-12-06 15:56 ` Markus F.X.J. Oberhumer
2018-11-30 14:26 ` [PATCH 3/8] lib/lzo: enable 64-bit CTZ on Arm Dave Rodgman
2018-12-06 15:51 ` Markus F.X.J. Oberhumer
2018-11-30 14:26 ` [PATCH 4/8] lib/lzo: 64-bit CTZ on arm64 Dave Rodgman
2018-12-06 15:52 ` Markus F.X.J. Oberhumer
2018-11-30 14:26 ` [PATCH 5/8] lib/lzo: fast 8-byte copy " Dave Rodgman
2018-12-06 15:53 ` Markus F.X.J. Oberhumer
2018-11-30 14:26 ` [PATCH 6/8] lib/lzo: implement run-length encoding Dave Rodgman
2018-12-06 15:56 ` Markus F.X.J. Oberhumer
2018-11-30 14:26 ` [PATCH 7/8] lib/lzo: separate lzo-rle from lzo Dave Rodgman
2018-12-01 8:48 ` Herbert Xu
2018-11-30 14:26 ` [PATCH 8/8] zram: default to lzo-rle instead of lzo Dave Rodgman
2018-12-05 7:30 ` [PATCH v4 0/7] lib/lzo: performance improvements Sergey Senozhatsky
2018-12-05 9:50 ` Dave Rodgman
2018-12-05 10:20 ` Sergey Senozhatsky
2018-12-06 15:47 ` Markus F.X.J. Oberhumer
2018-12-06 16:22 ` Matt Sealey
2018-12-07 15:54 ` Dave Rodgman [this message]
2019-01-07 15:35 ` Dave Rodgman
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