Messages in this thread | | | From | Nadav Amit <> | Subject | Re: [PATCH v2 8/9] x86/mm/tlb: Remove UV special case | Date | Tue, 9 Jul 2019 21:09:13 +0000 |
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> On Jul 9, 2019, at 1:29 PM, Mike Travis <mike.travis@hpe.com> wrote: > > > > On 7/9/2019 1:09 PM, Russ Anderson wrote: >> On Tue, Jul 09, 2019 at 09:50:27PM +0200, Thomas Gleixner wrote: >>> On Tue, 2 Jul 2019, Nadav Amit wrote: >>> >>>> SGI UV support is outdated and not maintained, and it is not clear how >>>> it performs relatively to non-UV. Remove the code to simplify the code. >>> >>> You should at least Cc the SGI/HP folks on that. They are still >>> around. Done so. >> Thanks Thomas. The SGI UV is now HPE Superdome Flex and is >> very much still supported. >> Thanks. >>>> Cc: Peter Zijlstra <peterz@infradead.org> >>>> Cc: Dave Hansen <dave.hansen@intel.com> >>>> Suggested-by: Andy Lutomirski <luto@kernel.org> >>>> Signed-off-by: Nadav Amit <namit@vmware.com> >>>> --- >>>> arch/x86/mm/tlb.c | 25 ------------------------- >>>> 1 file changed, 25 deletions(-) >>>> >>>> diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c >>>> index b47a71820f35..64afe1215495 100644 >>>> --- a/arch/x86/mm/tlb.c >>>> +++ b/arch/x86/mm/tlb.c >>>> @@ -689,31 +689,6 @@ void native_flush_tlb_multi(const struct cpumask *cpumask, >>>> trace_tlb_flush(TLB_REMOTE_SEND_IPI, >>>> (info->end - info->start) >> PAGE_SHIFT); >>>> - if (is_uv_system()) { >>>> - /* >>>> - * This whole special case is confused. UV has a "Broadcast >>>> - * Assist Unit", which seems to be a fancy way to send IPIs. >>>> - * Back when x86 used an explicit TLB flush IPI, UV was >>>> - * optimized to use its own mechanism. These days, x86 uses >>>> - * smp_call_function_many(), but UV still uses a manual IPI, >>>> - * and that IPI's action is out of date -- it does a manual >>>> - * flush instead of calling flush_tlb_func_remote(). This >>>> - * means that the percpu tlb_gen variables won't be updated >>>> - * and we'll do pointless flushes on future context switches. >>>> - * >>>> - * Rather than hooking native_flush_tlb_multi() here, I think >>>> - * that UV should be updated so that smp_call_function_many(), >>>> - * etc, are optimal on UV. >>>> - */ > > I thought this change was already proposed a bit ago and we acked it > awhile back. Also the replacement functionality is being worked on but it > is more complex. The smp call many has to support all the reasons why it’s > called and not just the tlb shoot downs as is the current BAU case.
Sorry for not cc’ing you before. In the meanwhile, can you give an explicit acked-by? (I couldn’t find the previous patch you regarded.)
Thanks, Nadav | |