Messages in this thread | | | Subject | Re: [PATCH] arm64: Increase the max granular size | From | Tirumalesh Chalamarla <> | Date | Fri, 25 Sep 2015 09:31:39 -0700 |
| |
On 09/25/2015 07:45 AM, Robert Richter wrote: > 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?
mainly for workloads where compiler optimizes based on cache line size, let me write a small bench mark > 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?
| |