From: "Aneesh Kumar K.V" <aneesh.kumar@linux•ibm.com>
To: Nick Piggin <npiggin@gmail•com>
Cc: Linus Torvalds <torvalds@linux-foundation•org>,
"linux-mm@kvack•org" <linux-mm@kvack•org>,
"kaleshsingh@google•com" <kaleshsingh@google•com>,
"joel@joelfernandes•org" <joel@joelfernandes•org>,
"Kirill A . Shutemov" <kirill@shutemov•name>,
"akpm@linux-foundation•org" <akpm@linux-foundation•org>,
"linuxppc-dev@lists•ozlabs.org" <linuxppc-dev@lists•ozlabs.org>
Subject: Re: [PATCH v7 00/11] Speedup mremap on ppc64
Date: Tue, 8 Jun 2021 10:09:36 +0530 [thread overview]
Message-ID: <3f2b7150-eaba-e1ab-bb88-53a3510727b9@linux.ibm.com> (raw)
In-Reply-To: <CAPa8GCAmgUyqqAcuLC7KxDvDepkqhhvVcwgSGJh92PT+LoMQcw@mail.gmail.com>
On 6/7/21 3:40 PM, Nick Piggin wrote:
> On Monday, 7 June 2021, Aneesh Kumar K.V <aneesh.kumar@linux•ibm.com>
> wrote: This patchset enables MOVE_PMD/MOVE_PUD support on power. This
> requires the platform to support updating higher-level page tables
> without updating page table ZjQcmQRYFpfptBannerStart
> This Message Is From an External Sender
> This message came from outside your organization.
> ZjQcmQRYFpfptBannerEnd
>
>
> On Monday, 7 June 2021, Aneesh Kumar K.V <aneesh.kumar@linux•ibm.com
> <mailto:aneesh.kumar@linux•ibm.com>> wrote:
>
>
> This patchset enables MOVE_PMD/MOVE_PUD support on power. This requires
> the platform to support updating higher-level page tables without
> updating page table entries. This also needs to invalidate the Page Walk
> Cache on architecture supporting the same.
>
> Changes from v6:
> * Update ppc64 flush_tlb_range to invalidate page walk cache.
>
>
> I'd really rather not do this, I'm not sure if micro bench mark captures
> everything.
>
> Page tables coming from L2/L3 probably aren't the primary purpose or
> biggest benefit of intermediate level caches.
>
> The situation on POWER with nest mmu (coherent accelerators) is
> magnified. They have huge page walk cashes to make up for the fact they
> don't have data caches for walking page tables which makes the
> invalidation more painful in terms of subsequent misses, but also
> latency to invalidate (can be order of microseconds whereas a page
> invalidate is a couple of orders of magnitude faster).
>
If we are using NestMMU, we already upgrade that flush to invalidate
page walk cache right? ie, if we have > PMD_SIZE range, we would upgrade
the invalidate to a pid flush via
flush_pid = nr_pages > tlb_single_page_flush_ceiling;
and if it is PID flush if we are using NestMMU we already upgrade a
RIC_FLUSH_TLB to RIC_FLUSH_ALL ?
> Yes it is a deficiency of the ppc invalidation architecture, we are
> aware and would like to improve it but for now those is what we have.
>
-aneesh
next prev parent reply other threads:[~2021-06-08 4:40 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-07 5:51 [PATCH v7 00/11] Speedup mremap on ppc64 Aneesh Kumar K.V
2021-06-07 5:51 ` [PATCH v7 01/11] mm/mremap: Fix race between MOVE_PMD mremap and pageout Aneesh Kumar K.V
2021-06-08 0:06 ` Hugh Dickins
2021-06-08 7:52 ` Aneesh Kumar K.V
2021-06-08 9:42 ` Kirill A. Shutemov
2021-06-08 11:17 ` Aneesh Kumar K.V
2021-06-08 12:05 ` Kirill A. Shutemov
2021-06-08 20:39 ` Hugh Dickins
2021-06-07 5:51 ` [PATCH v7 02/11] mm/mremap: Fix race between MOVE_PUD " Aneesh Kumar K.V
2021-06-14 14:55 ` [mm/mremap] ecf8443e51: vm-scalability.throughput -29.4% regression kernel test robot
2021-06-14 14:58 ` Linus Torvalds
2021-06-14 16:08 ` Aneesh Kumar K.V
2021-06-17 2:38 ` [LKP] " Liu, Yujie
2021-06-07 5:51 ` [PATCH v7 03/11] selftest/mremap_test: Update the test to handle pagesize other than 4K Aneesh Kumar K.V
2021-06-07 5:51 ` [PATCH v7 04/11] selftest/mremap_test: Avoid crash with static build Aneesh Kumar K.V
2021-06-07 5:51 ` [PATCH v7 05/11] mm/mremap: Convert huge PUD move to separate helper Aneesh Kumar K.V
2021-06-07 5:51 ` [PATCH v7 06/11] mm/mremap: Don't enable optimized PUD move if page table levels is 2 Aneesh Kumar K.V
2021-06-07 5:51 ` [PATCH v7 07/11] mm/mremap: Use pmd/pud_poplulate to update page table entries Aneesh Kumar K.V
2021-06-07 5:51 ` [PATCH v7 08/11] powerpc/mm/book3s64: Fix possible build error Aneesh Kumar K.V
2021-06-07 5:51 ` [PATCH v7 09/11] mm/mremap: Allow arch runtime override Aneesh Kumar K.V
2021-06-07 5:51 ` [PATCH v7 10/11] powerpc/book3s64/mm: Update flush_tlb_range to flush page walk cache Aneesh Kumar K.V
2021-06-07 5:51 ` [PATCH v7 11/11] powerpc/mm: Enable HAVE_MOVE_PMD support Aneesh Kumar K.V
2021-06-07 10:10 ` [PATCH v7 00/11] Speedup mremap on ppc64 Nick Piggin
2021-06-08 4:39 ` Aneesh Kumar K.V [this message]
2021-06-08 5:03 ` Nicholas Piggin
2021-06-08 17:10 ` Linus Torvalds
2021-06-16 1:44 ` Nicholas Piggin
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