From: "Nicholas Piggin" <npiggin@gmail.com>
To: "Linus Torvalds" <torvalds@linux-foundation.org>
Cc: "Mateusz Guzik" <mjguzik@gmail.com>,
"linux-arch" <linux-arch@vger.kernel.org>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Will Deacon" <will@kernel.org>,
"Michael Ellerman" <mpe@ellerman.id.au>, <tony.luck@intel.com>,
<viro@zeniv.linux.org.uk>, <linux-fsdevel@vger.kernel.org>,
"Jan Glauber" <jan.glauber@gmail.com>,
"linuxppc-dev" <linuxppc-dev@lists.ozlabs.org>,
"Linux ARM" <linux-arm-kernel@lists.infradead.org>
Subject: Re: lockref scalability on x86-64 vs cpu_relax
Date: Fri, 13 Jan 2023 15:36:10 +1000 [thread overview]
Message-ID: <CPQTHRRWI40R.5SDS94D8EFFA@bobo> (raw)
In-Reply-To: <CAHk-=wiRm+Z613bHt2d=N1yWJAiDiQVXkh0dN8z02yA_JS-rew@mail.gmail.com>
On Fri Jan 13, 2023 at 2:15 PM AEST, Linus Torvalds wrote:
> On Thu, Jan 12, 2023 at 9:20 PM Nicholas Piggin <npiggin@gmail.com> wrote:
> >
> > Actually what we'd really want is an arch specific implementation of
> > lockref.
>
> The problem is mainly that then you need to generate the asm versions
> of all those different CMPXCHG_LOOP() variants.
>
> They are all fairly simple, though, and it woudln't be hard to make
> the current lib/lockref.c just be the generic fallback if you don't
> have an arch-specific one.
Yeah, it doesn't look too onerous so it's probably worth seeing what
the code and some numbers look like here.
> And even if you do have the arch-specific LL/SC version, you'd still
> want the generic fallback for the case where a spinlock isn't a single
> word any more (which happens when the spinlock debugging options are
> on).
You're right, good point.
Thanks,
Nick
next prev parent reply other threads:[~2023-01-13 5:37 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-12 23:36 lockref scalability on x86-64 vs cpu_relax Mateusz Guzik
2023-01-13 0:13 ` Linus Torvalds
2023-01-13 0:30 ` Luck, Tony
2023-01-13 0:45 ` Linus Torvalds
2023-01-13 7:55 ` ia64 removal (was: Re: lockref scalability on x86-64 vs cpu_relax) Ard Biesheuvel
2023-01-13 16:17 ` Luck, Tony
2023-01-13 20:49 ` Jessica Clarke
2023-01-13 21:03 ` Luck, Tony
2023-01-13 21:04 ` Jessica Clarke
2023-01-13 21:05 ` John Paul Adrian Glaubitz
2023-01-13 23:25 ` Ard Biesheuvel
2023-01-14 11:24 ` Sedat Dilek
2023-01-14 11:28 ` Sedat Dilek
2023-01-15 0:27 ` Matthew Wilcox
2023-01-15 12:04 ` Sedat Dilek
2023-01-16 9:42 ` John Paul Adrian Glaubitz
2023-01-16 9:41 ` John Paul Adrian Glaubitz
2023-01-16 13:28 ` Matthew Wilcox
2023-01-16 9:40 ` John Paul Adrian Glaubitz
2023-01-16 9:37 ` John Paul Adrian Glaubitz
2023-01-16 9:32 ` John Paul Adrian Glaubitz
2023-01-16 10:09 ` Ard Biesheuvel
2023-01-13 1:12 ` lockref scalability on x86-64 vs cpu_relax Mateusz Guzik
2023-01-13 4:08 ` Linus Torvalds
2023-01-13 9:46 ` Will Deacon
2023-01-13 3:20 ` Nicholas Piggin
2023-01-13 4:15 ` Linus Torvalds
2023-01-13 5:36 ` Nicholas Piggin [this message]
2023-01-16 14:08 ` Memory transaction instructions David Howells
2023-01-16 15:09 ` Matthew Wilcox
2023-01-16 16:59 ` Linus Torvalds
2023-01-18 9:05 ` David Howells
2023-01-19 1:41 ` Nicholas Piggin
2023-01-13 10:23 ` lockref scalability on x86-64 vs cpu_relax Peter Zijlstra
2023-01-13 18:44 ` [PATCH] lockref: stop doing cpu_relax in the cmpxchg loop Mateusz Guzik
2023-01-13 21:47 ` Luck, Tony
2023-01-13 23:31 ` Linus Torvalds
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