From: Robert Richter <robert.richter@caviumnetworks.com>
To: Will Deacon <will.deacon@arm.com>
Cc: Robert Richter <rric@kernel.org>,
Catalin Marinas <Catalin.Marinas@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Tirumalesh Chalamarla <tchalamarla@cavium.com>
Subject: Re: [PATCH] arm64: Increase the max granular size
Date: Fri, 25 Sep 2015 16:45:16 +0200 [thread overview]
Message-ID: <20150925144516.GM1820@rric.localdomain> (raw)
In-Reply-To: <20150922182902.GO7356@arm.com>
Will,
On 22.09.15 19:29:02, Will Deacon wrote:
> On Tue, Sep 22, 2015 at 06:59:48PM +0100, Robert Richter wrote:
> > From: Tirumalesh Chalamarla <tchalamarla@cavium.com>
> >
> > Increase the standard cacheline size to avoid having locks in the same
> > cacheline.
> >
> > Cavium's ThunderX core implements cache lines of 128 byte size. With
> > current granulare size of 64 bytes (L1_CACHE_SHIFT=6) two locks could
> > share the same cache line leading a performance degradation.
> > Increasing the size fixes that.
>
> Do you have an example of that happening?
I did some 'poor man's kernel build all modules benchmarking' and
could not find significant performance improvements so far (second
part with the patch reverted):
build-allmodules-4.2.0-01404-g5818d6e89783.log:real 7m10.490s
build-allmodules-4.2.0-01404-g5818d6e89783.log:real 6m59.747s
build-allmodules-4.2.0-01404-g5818d6e89783.log:real 6m59.264s
build-allmodules-4.2.0-01404-g5818d6e89783.log:real 7m0.435s
build-allmodules-4.2.0-01404-g5818d6e89783.log:real 6m59.569s
build-allmodules-4.2.0-01404-g5818d6e89783.log:real 6m59.274s
build-allmodules-4.2.0-01404-g5818d6e89783.log:real 7m0.507s
build-allmodules-4.2.0-01404-g5818d6e89783.log:real 7m1.551s
build-allmodules-4.2.0-01404-g5818d6e89783.log:real 6m59.073s
build-allmodules-4.2.0-01404-g5818d6e89783.log:real 7m1.738s
build-allmodules-4.2.0-01406-g638c69fddc40.log:real 7m10.644s
build-allmodules-4.2.0-01406-g638c69fddc40.log:real 6m59.814s
build-allmodules-4.2.0-01406-g638c69fddc40.log:real 7m0.315s
build-allmodules-4.2.0-01406-g638c69fddc40.log:real 6m59.610s
build-allmodules-4.2.0-01406-g638c69fddc40.log:real 6m59.885s
build-allmodules-4.2.0-01406-g638c69fddc40.log:real 6m59.281s
build-allmodules-4.2.0-01406-g638c69fddc40.log:real 7m0.869s
build-allmodules-4.2.0-01406-g638c69fddc40.log:real 7m0.953s
build-allmodules-4.2.0-01406-g638c69fddc40.log:real 7m0.787s
build-allmodules-4.2.0-01406-g638c69fddc40.log:real 7m0.656s
I will check what kind of workloads this patch was written for.
Tirumalesh, any idea?
Thanks,
-Robert
>
> > Increasing the size has no negative impact to cache invalidation on
> > systems with a smaller cache line. There is an impact on memory usage,
> > but that's not too important for arm64 use cases.
>
> Do you have any before/after numbers to show the impact of this change
> on other supported SoCs?
next prev parent reply other threads:[~2015-09-25 15:01 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-22 17:59 [PATCH] arm64: Increase the max granular size Robert Richter
2015-09-22 18:29 ` Will Deacon
2015-09-25 14:45 ` Robert Richter [this message]
2015-09-25 16:31 ` Tirumalesh Chalamarla
2015-10-10 17:39 ` Timur Tabi
2015-10-12 9:16 ` Will Deacon
2015-10-16 19:57 ` Timur Tabi
2015-10-28 19:09 ` Catalin Marinas
2015-11-03 11:07 ` Geert Uytterhoeven
2015-11-03 12:05 ` Catalin Marinas
2015-11-03 14:38 ` Catalin Marinas
2015-11-03 14:55 ` Geert Uytterhoeven
2015-11-03 18:50 ` Catalin Marinas
2015-11-03 23:33 ` Christoph Lameter
2015-11-04 12:36 ` Catalin Marinas
2015-11-04 13:53 ` Christoph Lameter
2015-11-04 14:54 ` Catalin Marinas
2015-11-04 15:28 ` Christoph Lameter
2015-11-04 15:39 ` Catalin Marinas
2015-11-05 4:31 ` Joonsoo Kim
2015-11-05 11:50 ` [PATCH] mm: slab: Only move management objects off-slab for sizes larger than KMALLOC_MIN_SIZE Catalin Marinas
2015-11-05 13:31 ` Andrew Morton
2015-11-05 16:08 ` Catalin Marinas
2015-11-06 13:00 ` Geert Uytterhoeven
2015-11-05 17:39 ` Christoph Lameter
2015-11-05 4:40 ` [PATCH] arm64: Increase the max granular size Joonsoo Kim
2015-11-05 10:32 ` Catalin Marinas
2015-11-05 11:45 ` Joonsoo Kim
2015-11-05 12:17 ` Catalin Marinas
2015-11-09 7:41 ` Joonsoo Kim
2015-11-09 18:36 ` Catalin Marinas
2015-11-10 0:19 ` Joonsoo Kim
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