From: Barry Song <21cnbao@gmail.com>
To: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>,
LAK <linux-arm-kernel@lists.infradead.org>, x86 <x86@kernel.org>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Will Deacon" <will@kernel.org>,
"Linux Doc Mailing List" <linux-doc@vger.kernel.org>,
"Jonathan Corbet" <corbet@lwn.net>,
"Arnd Bergmann" <arnd@arndb.de>,
LKML <linux-kernel@vger.kernel.org>,
"Darren Hart" <darren@os.amperecomputing.com>,
"Yicong Yang" <yangyicong@hisilicon.com>,
huzhanyuan@oppo.com, "李培锋(wink)" <lipeifeng@oppo.com>,
"张诗明(Simon Zhang)" <zhangshiming@oppo.com>, 郭健 <guojian@oppo.com>,
"real mz" <realmz6@gmail.com>,
linux-mips@vger.kernel.org, openrisc@lists.librecores.org,
linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
linux-s390@vger.kernel.org, "Barry Song" <v-songbaohua@oppo.com>
Subject: Re: [PATCH v2 2/4] mm: rmap: Allow platforms without mm_cpumask to defer TLB flush
Date: Tue, 12 Jul 2022 10:52:24 +1200 [thread overview]
Message-ID: <CAGsJ_4wW=3xsmB1jzcv=sD9OhhPc0v=+odp=JY80vEbMY6OZ_g@mail.gmail.com> (raw)
In-Reply-To: <13b283fe-10f7-376f-9b8e-856e4d1e0ede@huawei.com>
On Tue, Jul 12, 2022 at 1:35 AM Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
>
> Hi Barry,
>
> On 2022/7/11 11:46, Barry Song wrote:
> > From: Barry Song <v-songbaohua@oppo.com>
> >
> > Platforms like ARM64 have hareware TLB shootdown broadcast. They
> > don't maintain mm_cpumask but just send tlbi and related sync
> > instructions for TLB flush. task's mm_cpumask is normally empty
> > in this case. We also allow deferred TLB flush on this kind of
> > platforms.
> >
> > Signed-off-by: Barry Song <v-songbaohua@oppo.com>>
> > ---
> ...
> > diff --git a/mm/Kconfig b/mm/Kconfig
> > index 169e64192e48..7bf54f57ca01 100644
> > --- a/mm/Kconfig
> > +++ b/mm/Kconfig
> > @@ -951,6 +951,9 @@ config ARCH_HAS_CURRENT_STACK_POINTER
> > register alias named "current_stack_pointer", this config can be
> > selected.
> >
> > +config ARCH_HAS_MM_CPUMASK
> > + bool
> > +
> > config ARCH_HAS_VM_GET_PAGE_PROT
> > bool
> >
> > diff --git a/mm/rmap.c b/mm/rmap.c
> > index 5bcb334cd6f2..13d4f9a1d4f1 100644
> > --- a/mm/rmap.c
> > +++ b/mm/rmap.c
> > @@ -692,6 +692,10 @@ static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
> > if (!(flags & TTU_BATCH_FLUSH))
> > return false;
> >
> > +#ifndef CONFIG_ARCH_HAS_MM_CPUMASK
> > + return true;
> > +#endif
> > +
>
> Here is another option to enable arch's tlbbatch defer
>
This option is even better than simply having ARCH_HAS_MM_CPUMASK
since arch might make decisions based on specific hardware characters.
for example,
https://lists.ozlabs.org/pipermail/linuxppc-dev/2017-November/165468.html
+bool arch_tlbbatch_should_defer(struct mm_struct *mm)
+{
+ if (!radix_enabled() || cpu_has_feature(CPU_FTR_POWER9_DD1))
+ return false;
+
+ if (!mm_is_thread_local(mm))
+ return true;
+
+ return false;
+}
In this case, having MM_CPUMASK doesn't necessarily mean tlbbatch is needed.
> [1]
> https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20171101101735.2318-2-khandual@linux.vnet.ibm.com/
>
> > /* If remote CPUs need to be flushed then defer batch the flush */
> > if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids)
> > should_defer = true;
Thanks
Barry
next prev parent reply other threads:[~2022-07-11 22:52 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-11 3:46 [PATCH v2 0/4] mm: arm64: bring up BATCHED_UNMAP_TLB_FLUSH Barry Song
2022-07-11 3:46 ` [PATCH v2 1/4] Revert "Documentation/features: mark BATCHED_UNMAP_TLB_FLUSH doesn't apply to ARM64" Barry Song
2022-07-11 3:46 ` [PATCH v2 2/4] mm: rmap: Allow platforms without mm_cpumask to defer TLB flush Barry Song
2022-07-11 13:35 ` Kefeng Wang
2022-07-11 22:52 ` Barry Song [this message]
2022-07-11 3:46 ` [PATCH v2 3/4] mm: rmap: Extend tlbbatch APIs to fit new platforms Barry Song
2022-07-11 3:46 ` [PATCH v2 4/4] arm64: support batched/deferred tlb shootdown during page reclamation Barry Song
2022-07-14 3:28 ` [PATCH v2 0/4] mm: arm64: bring up BATCHED_UNMAP_TLB_FLUSH Xin Hao
2022-07-14 4:51 ` Barry Song
2022-07-15 2:47 ` Yicong Yang
2022-07-18 13:28 ` Yicong Yang
2022-07-20 11:18 ` Barry Song
2022-07-23 9:22 ` xhao
2022-07-23 9:17 ` xhao
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAGsJ_4wW=3xsmB1jzcv=sD9OhhPc0v=+odp=JY80vEbMY6OZ_g@mail.gmail.com' \
--to=21cnbao@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=arnd@arndb.de \
--cc=catalin.marinas@arm.com \
--cc=corbet@lwn.net \
--cc=darren@os.amperecomputing.com \
--cc=guojian@oppo.com \
--cc=huzhanyuan@oppo.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-riscv@lists.infradead.org \
--cc=linux-s390@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=lipeifeng@oppo.com \
--cc=openrisc@lists.librecores.org \
--cc=realmz6@gmail.com \
--cc=v-songbaohua@oppo.com \
--cc=wangkefeng.wang@huawei.com \
--cc=will@kernel.org \
--cc=x86@kernel.org \
--cc=yangyicong@hisilicon.com \
--cc=zhangshiming@oppo.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).