On 03/13/2015 07:18 PM, David Rientjes wrote: > On Fri, 13 Mar 2015, Eric B Munson wrote: > >>>> --- a/mm/compaction.c >>>> +++ b/mm/compaction.c >>>> @@ -1046,6 +1046,8 @@ typedef enum { >>>> ISOLATE_SUCCESS, /* Pages isolated, migrate */ >>>> } isolate_migrate_t; >>>> >>>> +int sysctl_compact_unevictable; >>>> + >>>> /* >>>> * Isolate all pages that can be migrated from the first suitable block, >>>> * starting at the block pointed to by the migrate scanner pfn within >>> >>> I suspect that the use cases where users absolutely do not want >>> unevictable pages migrated are special cases, and it may make >>> sense to enable sysctl_compact_unevictable by default. >> >> Given that sysctl_compact_unevictable=0 is the way the kernel behaves >> now and the push back against always enabling compaction on unevictable >> pages, I left the default to be the behavior as it is today. I agree >> that this is likely the minority case, but I'd really like Peter Z or >> someone else from real time to say that they are okay with the default >> changing. >> > > It would be really disappointing to not enable this by default for !rt > kernels. We haven't migrated mlocked pages in the past by way of memory > compaction because it can theoretically result in consistent minor page > faults, but I haven't yet heard a !rt objection to enabling this. > > If the rt patchset is going to carry a patch to disable this
It does not have to carry a patch to disable something that can be disabled at run time. The smaller the realtime patchset has to be, the better. -- All rights reversed -- 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/