From: Dave Martin <Dave.Martin@arm.com>
To: Mark Brown <broonie@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Julien Grall <julien@xen.org>,
Zhang Lei <zhang.lei@jp.fujitsu.com>,
Daniel Kiss <Daniel.Kiss@arm.com>, Julien Grall <julien@xen.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v7 0/3] arm64/sve: Improve performance when handling SVE access traps
Date: Wed, 21 Jul 2021 17:38:12 +0100 [thread overview]
Message-ID: <20210721163811.GY4187@arm.com> (raw)
In-Reply-To: <20210721163429.GF4259@sirena.org.uk>
On Wed, Jul 21, 2021 at 05:34:29PM +0100, Mark Brown wrote:
> On Wed, Jul 21, 2021 at 03:33:54PM +0100, Dave Martin wrote:
>
> > While I think this was a worthwhile experiment, my concern here is that
> > while the approach taken in this series is reasonable, it doesn't seem
> > to reduce the amount of code or result in a net simplification. From my
> > side I think it's probably best to stick with what we have, until
> > someone comes up with something that's clearly easier to understand.
>
> I did find it was making it easier to understand some of what was going
> on TBH - I forget which specific bits but I found the whole model of
> specifying the goal state at a higher level clarified things for me.
> It's definitely not saving much in the way of code though and the code
> that was already merged to do the zeroing in place gives us most of the
> win with dramatically less code, it just doesn't help if we do context
> switch.
>
> > So, I'd still favour the version based on Julien's code, which is more
> > of an incremental change to what we already had (and I think was most of
> > the way there in your post recent version of it).
>
> I prefer Julien's approach too, the requirement to trigger the slow path
> on return to userspace doesn't really work with the newer approach
> AFAICT. If this gets resurrected I'll go back to the last _NO_FLUSH
> version.
OK, sounds fair -- thanks for the patience.
Cheers
---Dave
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prev parent reply other threads:[~2021-07-21 16:40 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-03 20:11 [PATCH v7 0/3] arm64/sve: Improve performance when handling SVE access traps Mark Brown
2021-03-03 20:11 ` [PATCH v7 1/3] arm64/sve: Remove redundant system_supports_sve() tests Mark Brown
2021-03-03 20:11 ` [PATCH v7 2/3] arm64/sve: Split TIF_SVE into separate execute and register state flags Mark Brown
2021-03-03 20:11 ` [PATCH v7 3/3] arm64/sve: Rework SVE trap access to minimise memory access Mark Brown
2021-03-03 20:18 ` [PATCH v7 0/3] arm64/sve: Improve performance when handling SVE access traps Mark Brown
2021-07-21 14:33 ` Dave Martin
2021-07-21 16:34 ` Mark Brown
2021-07-21 16:38 ` Dave Martin [this message]
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