From: Ard Biesheuvel <ardb@kernel.org>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Dave Martin <dave.martin@arm.com>,
Mark Brown <broonie@kernel.org>,
Eric Biggers <ebiggers@kernel.org>, Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [RFC PATCH 0/5] running kernel mode SIMD with softirqs disabled
Date: Thu, 14 Jan 2021 09:22:49 +0100 [thread overview]
Message-ID: <CAMj1kXHpXAuyomBi1mTopgfgzZni+oWe7AfZgMaK2gUGaiot_g@mail.gmail.com> (raw)
In-Reply-To: <20201219020433.GA11077@gondor.apana.org.au>
On Sat, 19 Dec 2020 at 03:05, Herbert Xu <herbert@gondor.apana.org.au> wrote:
>
> On Fri, Dec 18, 2020 at 06:01:01PM +0100, Ard Biesheuvel wrote:
> >
> > Questions:
> > - what did I miss or break horribly?
> > - does any of this matter for RT? AIUI, RT runs softirqs from a dedicated
> > kthread, so I don't think it cares.
> > - what would be a reasonable upper bound to keep softirqs disabled? I suppose
> > 100s of cycles or less is overkill, but I'm not sure how to derive a better
> > answer.
> > - could we do the same on x86, now that kernel_fpu_begin/end is no longer
> > expensive?
>
> If this approach works not only would it allow us to support the
> synchronous users better, it would also allow us to remove loads
> of cruft in the Crypto API that exist solely to support these SIMD
> code paths.
>
> So I eagerly await the assessment of the scheduler/RT folks on this
> approach.
>
Any insights here? Is there a ballpark upper bound for the duration of
a softirq disabled section? Other reasons why dis/enabling softirq
handling is a bad idea?
WARNING: multiple messages have this Message-ID (diff)
From: Ard Biesheuvel <ardb@kernel.org>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Peter Zijlstra <peterz@infradead.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Eric Biggers <ebiggers@kernel.org>,
Mark Brown <broonie@kernel.org>,
Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>, Dave Martin <dave.martin@arm.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC PATCH 0/5] running kernel mode SIMD with softirqs disabled
Date: Thu, 14 Jan 2021 09:22:49 +0100 [thread overview]
Message-ID: <CAMj1kXHpXAuyomBi1mTopgfgzZni+oWe7AfZgMaK2gUGaiot_g@mail.gmail.com> (raw)
In-Reply-To: <20201219020433.GA11077@gondor.apana.org.au>
On Sat, 19 Dec 2020 at 03:05, Herbert Xu <herbert@gondor.apana.org.au> wrote:
>
> On Fri, Dec 18, 2020 at 06:01:01PM +0100, Ard Biesheuvel wrote:
> >
> > Questions:
> > - what did I miss or break horribly?
> > - does any of this matter for RT? AIUI, RT runs softirqs from a dedicated
> > kthread, so I don't think it cares.
> > - what would be a reasonable upper bound to keep softirqs disabled? I suppose
> > 100s of cycles or less is overkill, but I'm not sure how to derive a better
> > answer.
> > - could we do the same on x86, now that kernel_fpu_begin/end is no longer
> > expensive?
>
> If this approach works not only would it allow us to support the
> synchronous users better, it would also allow us to remove loads
> of cruft in the Crypto API that exist solely to support these SIMD
> code paths.
>
> So I eagerly await the assessment of the scheduler/RT folks on this
> approach.
>
Any insights here? Is there a ballpark upper bound for the duration of
a softirq disabled section? Other reasons why dis/enabling softirq
handling is a bad idea?
_______________________________________________
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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-01-14 8:23 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-18 17:01 [RFC PATCH 0/5] running kernel mode SIMD with softirqs disabled Ard Biesheuvel
2020-12-18 17:01 ` Ard Biesheuvel
2020-12-18 17:01 ` [RFC PATCH 1/5] crypto: aead - disallow en/decrypt for non-task or non-softirq context Ard Biesheuvel
2020-12-18 17:01 ` Ard Biesheuvel
2020-12-18 17:01 ` [RFC PATCH 2/5] crypto: skcipher " Ard Biesheuvel
2020-12-18 17:01 ` Ard Biesheuvel
2020-12-18 17:01 ` [RFC PATCH 3/5] crypto: arm64/gcm-aes-ce - add NEON yield support Ard Biesheuvel
2020-12-18 17:01 ` Ard Biesheuvel
2020-12-18 17:01 ` [RFC PATCH 4/5] arm64: fpsimd: run kernel mode NEON with softirqs disabled Ard Biesheuvel
2020-12-18 17:01 ` Ard Biesheuvel
2021-01-19 16:00 ` Dave Martin
2021-01-19 16:00 ` Dave Martin
2021-01-19 16:29 ` Ard Biesheuvel
2021-01-19 16:29 ` Ard Biesheuvel
2021-01-20 15:44 ` Dave Martin
2021-01-20 15:44 ` Dave Martin
2021-02-15 18:30 ` Ard Biesheuvel
2021-02-15 18:30 ` Ard Biesheuvel
2020-12-18 17:01 ` [RFC PATCH 5/5] crypto: arm64/gcm-aes-ce - remove non-SIMD fallback path Ard Biesheuvel
2020-12-18 17:01 ` Ard Biesheuvel
2020-12-19 2:04 ` [RFC PATCH 0/5] running kernel mode SIMD with softirqs disabled Herbert Xu
2020-12-19 2:04 ` Herbert Xu
2021-01-14 8:22 ` Ard Biesheuvel [this message]
2021-01-14 8:22 ` Ard Biesheuvel
2021-02-16 10:09 ` Peter Zijlstra
2021-02-16 10:09 ` Peter Zijlstra
2021-02-16 10:35 ` Ard Biesheuvel
2021-02-16 10:35 ` Ard Biesheuvel
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