On Fri, Sep 04, 2015 at 05:40:57PM +0100, Suzuki K. Poulose wrote: > On 04/09/15 17:04, Yury Norov wrote: > >This patch is on top of https://lkml.org/lkml/2015/9/2/413 > > > >In master, there's only a single function - > > update_mixed_endian_el0_support > >And similar function is on review mentioned above. > > > >The algorithm for them is like this: > > - there's system-wide boolean marker for the feature that is > > initially enabled; > > - there's also updater for the feature that may disable it > > system-widely if feature is not supported on current CPU. > > - updater is called for each CPU on bootup. > > > >The problem is the way updater does its work. On each CPU, it > >unconditionally updates system-wide marker. For multi-core > >system it makes CPU issue invalidate message for a cache > >line containing marker. This invalidate increases cache > >contention for nothing, because there's a single marker reset > >that is really needed, and the others are useless. > > > >If the number of system-wide markers of this sort will grow, > >it may become a trouble on large-scale SOCs. The fix is trivial, > >though: do system-wide marker update conditionally, and preserve > >corresponding cache line in shared state for all update() calls, > >except, probably, one. > > As I have mentioned already, this patch (and the per feature functions) > won't be needed once we merge my series (which is waiting for the merge > window to see the public lights) >
OK. Than waiting for your patchset. BR, Yury > Cheers > Suzuki -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
