From mboxrd@z Thu Jan 1 00:00:00 1970 From: haojian.zhuang@linaro.org (Haojian Zhuang) Date: Tue, 15 Apr 2014 14:45:05 +0800 Subject: [PATCH v2 06/12] ARM: mcpm: change max clusters to 4 In-Reply-To: References: <1396944052-9887-1-git-send-email-haojian.zhuang@linaro.org> <1396944052-9887-7-git-send-email-haojian.zhuang@linaro.org> <20140410095650.GA5499@e103592.cambridge.arm.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 11 April 2014 10:39, Nicolas Pitre wrote: > On Thu, 10 Apr 2014, Dave Martin wrote: > >> On Tue, Apr 08, 2014 at 04:00:46PM +0800, Haojian Zhuang wrote: >> > In order to support 4 clusters with 4 Cortex A15 Cores in each cluster, >> > enlarge maximum clusters from 2 to 4 in MCPM. >> >> CC Nico on mcpm patches please. I'm happy to be CC'd as well. > > Indeed. > >> > Signed-off-by: Haojian Zhuang >> > --- >> > arch/arm/include/asm/mcpm.h | 2 +- >> > 1 file changed, 1 insertion(+), 1 deletion(-) >> > >> > diff --git a/arch/arm/include/asm/mcpm.h b/arch/arm/include/asm/mcpm.h >> > index 608516e..68f82cf 100644 >> > --- a/arch/arm/include/asm/mcpm.h >> > +++ b/arch/arm/include/asm/mcpm.h >> > @@ -20,7 +20,7 @@ >> > * to consider dynamic allocation. >> > */ >> > #define MAX_CPUS_PER_CLUSTER 4 >> > -#define MAX_NR_CLUSTERS 2 >> > +#define MAX_NR_CLUSTERS 4 >> >> Because of the need for alignment to the biggest cacheline size in the >> system, the MCPM low-level locking structures consume a non-trivial >> amount of memory. >> >> Therefore, I'm not keen on the idea of simply increasing this #define >> every time a platform appears with a larger number of clusters. >> If hip04 is not built into the kernel, this just wastes memory. >> >> I'll leave it to Nico to decide whether we can increase the #define >> to 4 or whether this needs a proper fix now. Ideally, we would have >> a way of choosing the maximum value required by the set of boards built >> into the kernel, or switch to dynamic allocation. > > I think we should go with the ability to select a maximum based on the > configured platforms. That could be as simple as having a > CONFIG_MCPM_QUAD_CLUSTER symbol to be selected by those platforms that > need it. > I'll set MAX_NR_CLUSTERS from Kconfig. If BIG_LITTLE isn't enabled & HIP04 is enabled, MAX_NR_CLUSTERS could be set to 4. Otherwise, it's always 2. Since there're only 16 A15 cores in HiP04. Regards Haojian