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From: "Chalamarla, Tirumalesh" <Tirumalesh.Chalamarla@caviumnetworks.com>
To: Ganesh Mahendran <opensource.ganesh@gmail.com>,
	"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
	"will.deacon@arm.com" <will.deacon@arm.com>
Cc: "stable@vger.kernel.org" <stable@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] Revert "arm64: Increase the max granular size"
Date: Fri, 18 Mar 2016 21:05:37 +0000	[thread overview]
Message-ID: <DA22064C-45A7-4F79-A433-84054AF182DF@caviumnetworks.com> (raw)
In-Reply-To: <1458120743-12145-1-git-send-email-opensource.ganesh@gmail.com>






On 3/16/16, 2:32 AM, "linux-arm-kernel on behalf of Ganesh Mahendran" <linux-arm-kernel-bounces@lists.infradead.org on behalf of opensource.ganesh@gmail.com> wrote:

>Reverts commit 97303480753e ("arm64: Increase the max granular size").
>
>The commit 97303480753e ("arm64: Increase the max granular size") will
>degrade system performente in some cpus.
>
>We test wifi network throughput with iperf on Qualcomm msm8996 CPU:
>----------------
>run on host:
>  # iperf -s
>run on device:
>  # iperf -c <device-ip-addr> -t 100 -i 1
>----------------
>
>Test result:
>----------------
>with commit 97303480753e ("arm64: Increase the max granular size"):
>    172MBits/sec
>
>without commit 97303480753e ("arm64: Increase the max granular size"):
>    230MBits/sec
>----------------
>
>Some module like slab/net will use the L1_CACHE_SHIFT, so if we do not
>set the parameter correctly, it may affect the system performance.
>
>So revert the commit.

Is there any explanation why is this so? May be there is an alternative to this, apart from reverting the commit.

Until now it seems L1_CACHE_SHIFT is the max of supported chips. But now we are making it 64byte, is there any reason why not 32. 

Thanks,
Tirumalesh. 
>
>Cc: stable@vger.kernel.org
>Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
>---
> arch/arm64/include/asm/cache.h |    2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/arch/arm64/include/asm/cache.h b/arch/arm64/include/asm/cache.h
>index 5082b30..bde4499 100644
>--- a/arch/arm64/include/asm/cache.h
>+++ b/arch/arm64/include/asm/cache.h
>@@ -18,7 +18,7 @@
> 
> #include <asm/cachetype.h>
> 
>-#define L1_CACHE_SHIFT		7
>+#define L1_CACHE_SHIFT		6
> #define L1_CACHE_BYTES		(1 << L1_CACHE_SHIFT)
> 
> /*
>-- 
>1.7.9.5
>
>
>_______________________________________________
>linux-arm-kernel mailing list
>linux-arm-kernel@lists.infradead.org
>http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2016-03-18 21:05 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-16  9:32 [PATCH] Revert "arm64: Increase the max granular size" Ganesh Mahendran
2016-03-16 10:07 ` Will Deacon
2016-03-16 13:06   ` Timur Tabi
2016-03-16 14:03     ` Mark Rutland
2016-03-16 14:35       ` Will Deacon
2016-03-16 14:54         ` Mark Rutland
2016-03-16 14:18     ` Catalin Marinas
2016-03-16 15:26       ` Timur Tabi
2016-03-17 14:27         ` Catalin Marinas
2016-03-17 14:49           ` Timur Tabi
2016-03-17 15:37             ` Catalin Marinas
2016-03-17 16:03               ` Marc Zyngier
2016-03-17 18:07           ` Andrew Pinski
2016-03-17 18:34             ` Timur Tabi
2016-03-17 18:37             ` Catalin Marinas
2016-03-18 21:05 ` Chalamarla, Tirumalesh [this message]
2016-03-21  1:56   ` Ganesh Mahendran
2016-03-21 17:14   ` Catalin Marinas
2016-03-21 17:23     ` Will Deacon
2016-03-21 17:33       ` Catalin Marinas
2016-03-21 17:39         ` Chalamarla, Tirumalesh
     [not found]     ` <CAPub14-sFgx=oCHzJPb9h9b_V0rbn5UAMDNJ-yTkjhz38JPqMQ@mail.gmail.com>
     [not found]       ` <10fef112-37f1-0a1b-b5af-435acd032f01@codeaurora.org>
2017-04-06  7:22         ` Imran Khan
2017-04-06 15:58           ` Catalin Marinas
2017-04-07  2:06             ` Ganesh Mahendran
2017-04-07  8:59               ` Catalin Marinas
2017-04-12  5:13               ` Imran Khan
2017-04-12 14:00                 ` Chalamarla, Tirumalesh
2017-04-17  7:35                   ` Imran Khan
2017-04-17 10:38                     ` Sunil Kovvuri
2017-04-18 14:48                       ` Catalin Marinas
2017-04-18 17:05                         ` Sunil Kovvuri
2017-04-19 12:01                           ` Catalin Marinas
2017-04-19 13:11                             ` Sunil Kovvuri
2017-04-25  6:42                               ` Ding Tianhong
2017-04-18 18:21                     ` Chalamarla, Tirumalesh
2017-04-11  4:40             ` Jon Masters

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