On 16/06/15 12:59, Jan Beulich wrote: >>>> On 16.06.15 at 13:14, <julien.gr...@citrix.com> wrote: >> On 15/06/2015 16:48, David Vrabel wrote: >>> diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h >>> index 44ea92d..a0ff9d2 100644 >>> --- a/xen/include/xen/sched.h >>> +++ b/xen/include/xen/sched.h >>> @@ -129,7 +129,7 @@ struct evtchn >>> #endif >>> } ssid; >>> #endif >>> -}; >>> +} __attribute__((aligned(64))); >> >> Why don't you use __cacheline_aligned? > > That would double the size on x86, for little or no benefit.
Well, the cache line size is not necessarily 64 bytes on every architecture. In the case of ARM, the cache line depends on the processor version. __cacheline_aligned is the only way to ensure that the cache line is not shared on ARM. AFAIU, the goal of this patch is to avoid sharing the cache line. If not, the commit message is misleading because it claims that a cache line is always 64 bytes... Regards, -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
