From: Bob Liu <bob.liu@oracle.com>
To: Martin Steigerwald <Martin@lichtvoll.de>
Cc: Seth Jennings <sjenning@linux.vnet.ibm.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: zswap: How to determine whether it is compressing swap pages?
Date: Thu, 18 Jul 2013 20:43:40 +0800 [thread overview]
Message-ID: <51E7E2FC.3070807@oracle.com> (raw)
In-Reply-To: <3125575.Ki4S75m1kx@merkaba>
Hi Martin,
On 07/18/2013 03:38 AM, Martin Steigerwald wrote:
> Am Mittwoch, 17. Juli 2013, 09:38:34 schrieb Seth Jennings:
>> On Wed, Jul 17, 2013 at 01:41:44PM +0200, Martin Steigerwald wrote:
>>> Is there any way to run zcache concurrently with zswap? I.e. use zcache only
>>> for read caches for filesystem and zswap for swap?
>>
>> No, at least not with zcache's frontswap features enabled. frontswap is a very
>> simple API that allows only one "backend" to register with it at a time. So
>> that means _either_ zswap or zcache.
>>
>> The only way they can be used in a meaningful way together is to use the
>> "nofrontswap" zcache option in the kernel boot parameters to prevent
>> zcache overriding zswap's frontswap registration.
>>
>> But the general answer is no, they shouldn't be used together.
>>
>>
>>>
>>> What is better suited for swap? zswap or zcache?
>>
>> zswap targets the specific case of caching swapped out pages in a compressed
>> cache and this is much simpler than zcache. zswap is also in mainline as of
>> 3.11-rc1.
>
> Thanks.
>
> Okay, then I will test zswap for now. I have a nice use case for it: Playing
Could you make some test by kernel compiling? Something like kernbench.
During my testing, I found that the swap ins/outs operations reduced but
the kernel compile time didn't reduce accordingly.
--
Regards,
-Bob
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WARNING: multiple messages have this Message-ID (diff)
From: Bob Liu <bob.liu@oracle.com>
To: Martin Steigerwald <Martin@lichtvoll.de>
Cc: Seth Jennings <sjenning@linux.vnet.ibm.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: zswap: How to determine whether it is compressing swap pages?
Date: Thu, 18 Jul 2013 20:43:40 +0800 [thread overview]
Message-ID: <51E7E2FC.3070807@oracle.com> (raw)
In-Reply-To: <3125575.Ki4S75m1kx@merkaba>
Hi Martin,
On 07/18/2013 03:38 AM, Martin Steigerwald wrote:
> Am Mittwoch, 17. Juli 2013, 09:38:34 schrieb Seth Jennings:
>> On Wed, Jul 17, 2013 at 01:41:44PM +0200, Martin Steigerwald wrote:
>>> Is there any way to run zcache concurrently with zswap? I.e. use zcache only
>>> for read caches for filesystem and zswap for swap?
>>
>> No, at least not with zcache's frontswap features enabled. frontswap is a very
>> simple API that allows only one "backend" to register with it at a time. So
>> that means _either_ zswap or zcache.
>>
>> The only way they can be used in a meaningful way together is to use the
>> "nofrontswap" zcache option in the kernel boot parameters to prevent
>> zcache overriding zswap's frontswap registration.
>>
>> But the general answer is no, they shouldn't be used together.
>>
>>
>>>
>>> What is better suited for swap? zswap or zcache?
>>
>> zswap targets the specific case of caching swapped out pages in a compressed
>> cache and this is much simpler than zcache. zswap is also in mainline as of
>> 3.11-rc1.
>
> Thanks.
>
> Okay, then I will test zswap for now. I have a nice use case for it: Playing
Could you make some test by kernel compiling? Something like kernbench.
During my testing, I found that the swap ins/outs operations reduced but
the kernel compile time didn't reduce accordingly.
--
Regards,
-Bob
next prev parent reply other threads:[~2013-07-18 12:43 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-17 10:04 zswap: How to determine whether it is compressing swap pages? Martin Steigerwald
2013-07-17 10:04 ` Martin Steigerwald
2013-07-17 10:36 ` Wanpeng Li
2013-07-17 10:36 ` Wanpeng Li
2013-07-17 10:42 ` Bob Liu
2013-07-17 10:42 ` Bob Liu
2013-07-17 11:41 ` Martin Steigerwald
2013-07-17 11:41 ` Martin Steigerwald
[not found] ` <20130717143834.GA4379@variantweb.net>
2013-07-17 19:38 ` Martin Steigerwald
2013-07-17 19:38 ` Martin Steigerwald
2013-07-18 12:43 ` Bob Liu [this message]
2013-07-18 12:43 ` Bob Liu
2013-07-18 17:36 ` Valdis.Kletnieks
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