From: Nadav Amit <namit@vmware.com>
To: Mike Travis <mike.travis@hpe.com>
Cc: Russ Anderson <rja@hpe.com>, Thomas Gleixner <tglx@linutronix.de>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
"x86@kernel.org" <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@intel.com>,
Dimitri Sivanich <sivanich@hpe.com>,
Hedi Berriche <hedi.berriche@hpe.com>
Subject: Re: [PATCH v2 8/9] x86/mm/tlb: Remove UV special case
Date: Tue, 9 Jul 2019 21:09:13 +0000 [thread overview]
Message-ID: <3AA5020A-111F-48F4-A0E9-B3C09E5EC43E@vmware.com> (raw)
In-Reply-To: <373adfb0-0047-eae2-46a5-041caddfca97@hpe.com>
> 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 SGI UV support is outdated and not maintained, and it is not clear how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 - * and that IPI's action is out of date -- it does a manual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
next prev parent reply other threads:[~2019-07-09 21:09 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-02 23:51 [PATCH v2 0/9] x86: Concurrent TLB flushes Nadav Amit
2019-07-02 23:51 ` [PATCH v2 1/9] smp: Run functions concurrently in smp_call_function_many() Nadav Amit
2019-07-02 23:51 ` [PATCH v2 2/9] x86/mm/tlb: Remove reason as argument for flush_tlb_func_local() Nadav Amit
2019-07-02 23:51 ` [PATCH v2 3/9] x86/mm/tlb: Open-code on_each_cpu_cond_mask() for tlb_is_not_lazy() Nadav Amit
2019-07-02 23:51 ` [PATCH v2 4/9] x86/mm/tlb: Flush remote and local TLBs concurrently Nadav Amit
2019-07-03 14:04 ` Juergen Gross
2019-07-03 17:02 ` Nadav Amit
2019-07-03 17:43 ` [Xen-devel] " Andrew Cooper
2019-07-03 18:09 ` Nadav Amit
2019-07-02 23:51 ` [PATCH v2 5/9] x86/mm/tlb: Privatize cpu_tlbstate Nadav Amit
2019-07-02 23:51 ` [PATCH v2 6/9] x86/mm/tlb: Do not make is_lazy dirty for no reason Nadav Amit
2019-07-02 23:51 ` [PATCH v2 7/9] cpumask: Mark functions as pure Nadav Amit
2019-07-02 23:51 ` [PATCH v2 8/9] x86/mm/tlb: Remove UV special case Nadav Amit
2019-07-09 19:50 ` Thomas Gleixner
2019-07-09 20:09 ` Russ Anderson
2019-07-09 20:29 ` Mike Travis
2019-07-09 21:09 ` Nadav Amit [this message]
2019-07-09 21:17 ` Mike Travis
2019-07-02 23:51 ` [PATCH v2 9/9] x86/mm/tlb: Remove unnecessary uses of the inline keyword Nadav Amit
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