From: Atish Patra <Atish.Patra@wdc.com>
To: "anup@brainfault.org" <anup@brainfault.org>,
"hch@infradead.org" <hch@infradead.org>
Cc: "aou@eecs.berkeley.edu" <aou@eecs.berkeley.edu>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
Anup Patel <Anup.Patel@wdc.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"alexios.zavras@intel.com" <alexios.zavras@intel.com>,
"palmer@sifive.com" <palmer@sifive.com>,
"paul.walmsley@sifive.com" <paul.walmsley@sifive.com>,
"linux-riscv@lists.infradead.org"
<linux-riscv@lists.infradead.org>,
"allison@lohutok.net" <allison@lohutok.net>
Subject: Re: [PATCH] RISC-V: Issue a local tlb flush if possible.
Date: Tue, 20 Aug 2019 00:02:31 +0000 [thread overview]
Message-ID: <797e3d1cd06dfc98cca0b595a738d297e9e858be.camel@wdc.com> (raw)
In-Reply-To: <20190819151015.GA3316@infradead.org>
On Mon, 2019-08-19 at 08:10 -0700, hch@infradead.org wrote:
> On Mon, Aug 19, 2019 at 08:39:02PM +0530, Anup Patel wrote:
> > If we were using ASID then yes we don't need to flush anything
> > but currently we don't use ASID due to lack of HW support and
> > HW can certainly do speculatively page table walks so flushing
> > local TLB when MM mask is empty might help.
> >
> > This just my theory and we need to stress test more.
>
> Well, when we context switch away from a mm we always flush the
> local tlb. So either the mm_struct has never been scheduled in,
Looking at the stack dump, it looks like this is the case. cpumask is
empty possibly after a fork/exec situation where forked child is being
replaced with actual program that is about to run.
I also looked at x86 & powerpc implementation which doesn't seem to do
anything special if cpumask is empty.
I will send a v2 with no tlb flushing if cpumask is empty.
> or we alrady did a local_tlb_flush and we context switched it up.
Regards,
Atish
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next prev parent reply other threads:[~2019-08-20 0:03 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-10 1:43 [PATCH] RISC-V: Issue a local tlb flush if possible Atish Patra
2019-08-10 3:30 ` Anup Patel
2019-08-10 5:28 ` Atish Patra
2019-08-10 6:37 ` Andreas Schwab
2019-08-10 9:21 ` Atish Patra
2019-08-12 14:56 ` Christoph Hellwig
2019-08-13 0:15 ` Atish Patra
2019-08-13 14:30 ` hch
2019-08-15 20:37 ` Atish Patra
2019-08-19 14:46 ` hch
2019-08-19 15:09 ` Anup Patel
2019-08-19 15:10 ` hch
2019-08-20 0:02 ` Atish Patra [this message]
2019-08-12 15:36 ` Troy Benjegerdes
2019-08-12 17:13 ` Atish Patra
2019-08-12 17:55 ` Christoph Hellwig
2019-08-13 18:25 ` Paul Walmsley
2019-08-14 1:49 ` Atish Patra
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