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From: Seth Jennings <sjenning@linux.vnet.ibm.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Dan Magenheimer <dan.magenheimer@oracle.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Nitin Gupta <ngupta@vflare.org>,
	Robert Jennings <rcj@linux.vnet.ibm.com>,
	linux-mm@kvack.org, devel@driverdev.osuosl.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/4] zsmalloc improvements
Date: Wed, 11 Jul 2012 09:00:30 -0500	[thread overview]
Message-ID: <4FFD86FE.1090307@linux.vnet.ibm.com> (raw)
In-Reply-To: <4FFD2524.2050300@kernel.org>

On 07/11/2012 02:03 AM, Minchan Kim wrote:
> On 07/03/2012 06:15 AM, Seth Jennings wrote:
>> zsmapbench measures the copy-based mapping at ~560 cycles for a
>> map/unmap operation on spanned object for both KVM guest and bare-metal,
>> while the page table mapping was ~1500 cycles on a VM and ~760 cycles
>> bare-metal.  The cycles for the copy method will vary with
>> allocation size, however, it is still faster even for the largest
>> allocation that zsmalloc supports.
>>
>> The result is convenient though, as mempcy is very portable :)
> 
> Today, I tested zsmapbench in my embedded board(ARM).
> tlb-flush is 30% faster than copy-based so it's always not win.
> I think it depends on CPU speed/cache size.
> 
> zram is already very popular on embedded systems so I want to use
> it continuously without 30% big demage so I want to keep our old approach
> which supporting local tlb flush. 
> 
> Of course, in case of KVM guest, copy-based would be always bin win.
> So shouldn't we support both approach? It could make code very ugly
> but I think it has enough value.
> 
> Any thought?

Thanks for testing on ARM.

I can add the pgtable assisted method back in, no problem.
The question is by which criteria are we going to choose
which method to use? By arch (i.e. ARM -> pgtable assist,
x86 -> copy, other archs -> ?)?

Also, what changes did you make to zsmapbench to measure
elapsed time/cycles on ARM?  Afaik, rdtscll() is not
supported on ARM.

Thanks,
Seth


WARNING: multiple messages have this Message-ID
From: Seth Jennings <sjenning@linux.vnet.ibm.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Dan Magenheimer <dan.magenheimer@oracle.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Nitin Gupta <ngupta@vflare.org>,
	Robert Jennings <rcj@linux.vnet.ibm.com>,
	linux-mm@kvack.org, devel@driverdev.osuosl.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/4] zsmalloc improvements
Date: Wed, 11 Jul 2012 09:00:30 -0500	[thread overview]
Message-ID: <4FFD86FE.1090307@linux.vnet.ibm.com> (raw)
In-Reply-To: <4FFD2524.2050300@kernel.org>

On 07/11/2012 02:03 AM, Minchan Kim wrote:
> On 07/03/2012 06:15 AM, Seth Jennings wrote:
>> zsmapbench measures the copy-based mapping at ~560 cycles for a
>> map/unmap operation on spanned object for both KVM guest and bare-metal,
>> while the page table mapping was ~1500 cycles on a VM and ~760 cycles
>> bare-metal.  The cycles for the copy method will vary with
>> allocation size, however, it is still faster even for the largest
>> allocation that zsmalloc supports.
>>
>> The result is convenient though, as mempcy is very portable :)
> 
> Today, I tested zsmapbench in my embedded board(ARM).
> tlb-flush is 30% faster than copy-based so it's always not win.
> I think it depends on CPU speed/cache size.
> 
> zram is already very popular on embedded systems so I want to use
> it continuously without 30% big demage so I want to keep our old approach
> which supporting local tlb flush. 
> 
> Of course, in case of KVM guest, copy-based would be always bin win.
> So shouldn't we support both approach? It could make code very ugly
> but I think it has enough value.
> 
> Any thought?

Thanks for testing on ARM.

I can add the pgtable assisted method back in, no problem.
The question is by which criteria are we going to choose
which method to use? By arch (i.e. ARM -> pgtable assist,
x86 -> copy, other archs -> ?)?

Also, what changes did you make to zsmapbench to measure
elapsed time/cycles on ARM?  Afaik, rdtscll() is not
supported on ARM.

Thanks,
Seth

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  reply	other threads:[~2012-07-11 14:01 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-07-02 21:15 Seth Jennings
2012-07-02 21:15 ` Seth Jennings
2012-07-02 21:15 ` [PATCH 1/4] zsmalloc: remove x86 dependency Seth Jennings
2012-07-02 21:15   ` Seth Jennings
2012-07-10  2:21   ` Minchan Kim
2012-07-10  2:21     ` Minchan Kim
2012-07-10 15:29     ` Seth Jennings
2012-07-10 15:29       ` Seth Jennings
2012-07-11  7:27       ` Minchan Kim
2012-07-11  7:27         ` Minchan Kim
2012-07-11 18:26   ` Nitin Gupta
2012-07-11 18:26     ` Nitin Gupta
2012-07-11 20:32     ` Seth Jennings
2012-07-11 20:32       ` Seth Jennings
2012-07-11 22:42       ` Nitin Gupta
2012-07-11 22:42         ` Nitin Gupta
2012-07-12  0:23         ` Seth Jennings
2012-07-12  0:23           ` Seth Jennings
2012-07-02 21:15 ` [PATCH 2/4] zsmalloc: add single-page object fastpath in unmap Seth Jennings
2012-07-02 21:15   ` Seth Jennings
2012-07-10  2:25   ` Minchan Kim
2012-07-10  2:25     ` Minchan Kim
2012-07-02 21:15 ` [PATCH 3/4] zsmalloc: add details to zs_map_object boiler plate Seth Jennings
2012-07-02 21:15   ` Seth Jennings
2012-07-10  2:35   ` Minchan Kim
2012-07-10  2:35     ` Minchan Kim
2012-07-10 15:17     ` Seth Jennings
2012-07-10 15:17       ` Seth Jennings
2012-07-11  7:42       ` Minchan Kim
2012-07-11  7:42         ` Minchan Kim
2012-07-11 14:15         ` Seth Jennings
2012-07-11 14:15           ` Seth Jennings
2012-07-12  1:15           ` Minchan Kim
2012-07-12  1:15             ` Minchan Kim
2012-07-12 19:54             ` Dan Magenheimer
2012-07-12 19:54               ` Dan Magenheimer
2012-07-12 22:46               ` Dan Magenheimer
2012-07-12 22:46                 ` Dan Magenheimer
2012-07-02 21:15 ` [PATCH 4/4] zsmalloc: add mapping modes Seth Jennings
2012-07-02 21:15   ` Seth Jennings
2012-07-04  5:33 ` [PATCH 0/4] zsmalloc improvements Minchan Kim
2012-07-04  5:33   ` Minchan Kim
2012-07-04 20:43 ` Konrad Rzeszutek Wilk
2012-07-04 20:43   ` Konrad Rzeszutek Wilk
2012-07-06 15:07   ` Seth Jennings
2012-07-06 15:07     ` Seth Jennings
2012-07-09 13:58     ` Seth Jennings
2012-07-09 13:58       ` Seth Jennings
2012-07-11 19:42       ` Konrad Rzeszutek Wilk
2012-07-11 19:42         ` Konrad Rzeszutek Wilk
2012-07-11 20:48         ` Seth Jennings
2012-07-11 20:48           ` Seth Jennings
2012-07-12 10:40           ` Konrad Rzeszutek Wilk
2012-07-12 10:40             ` Konrad Rzeszutek Wilk
2012-07-11  7:03 ` Minchan Kim
2012-07-11  7:03   ` Minchan Kim
2012-07-11 14:00   ` Seth Jennings [this message]
2012-07-11 14:00     ` Seth Jennings
2012-07-12  1:01     ` Minchan Kim
2012-07-12  1:01       ` Minchan Kim
2012-07-11 19:16   ` Seth Jennings
2012-07-11 19:16     ` Seth Jennings

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