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From: Eric Biggers <ebiggers@kernel.org>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jakub Kicinski <kuba@kernel.org>,
	fsverity@lists.linux.dev, linux-crypto@vger.kernel.org,
	dm-devel@lists.linux.dev, x86@kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
	Sami Tolvanen <samitolvanen@google.com>,
	Alasdair Kergon <agk@redhat.com>,
	Mike Snitzer <snitzer@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Mikulas Patocka <mpatocka@redhat.com>,
	David Howells <dhowells@redhat.com>,
	netdev@vger.kernel.org
Subject: Re: [PATCH v8 0/7] Optimize dm-verity and fsverity using multibuffer hashing
Date: Sat, 15 Feb 2025 19:26:16 -0800	[thread overview]
Message-ID: <20250216032616.GA90952@quark.localdomain> (raw)
In-Reply-To: <Z7FM9rhEA7n476EJ@gondor.apana.org.au>

On Sun, Feb 16, 2025 at 10:27:02AM +0800, Herbert Xu wrote:
> On Sat, Feb 15, 2025 at 09:04:12AM -0800, Jakub Kicinski wrote:
> >
> > Can confirm, FWIW. I don't know as much about IPsec, but for TLS
> > lightweight SW-only crypto would be ideal.
> 
> Please note that while CPU-only crypto is the best for networking,
> it actually operates in asynchronous mode on x86.  This is because
> RX occurs in softirq context, which may not be able to use SIMD on
> x86.

Well, the async fallback (using cryptd) occurs only when a kernel-mode FPU
section in process context is interrupted by a hardirq and at the end of it a
softirq also tries to use kernel-mode FPU.  It's generally a rare case but also
a terrible implementation that is really bad for performance; this should never
have been implemented this way.  I am planning to fix it so that softirqs on x86
will always be able to use the FPU, like they can on some of the other arches
like arm64 and riscv.

- Eric

  reply	other threads:[~2025-02-16  3:26 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20250212154718.44255-1-ebiggers@kernel.org>
2025-02-13  4:17 ` [PATCH v8 0/7] Optimize dm-verity and fsverity using multibuffer hashing Herbert Xu
2025-02-13  6:33   ` Eric Biggers
2025-02-14  2:44     ` Herbert Xu
2025-02-14  3:35       ` Eric Biggers
2025-02-14  3:50         ` Herbert Xu
2025-02-14  4:29           ` Eric Biggers
2025-02-14  4:56             ` Herbert Xu
2025-02-14  6:11               ` Eric Biggers
2025-02-14 10:50           ` Ard Biesheuvel
2025-02-15 17:04     ` Jakub Kicinski
2025-02-16  2:27       ` Herbert Xu
2025-02-16  3:26         ` Eric Biggers [this message]
2025-02-16  3:29           ` Herbert Xu
2025-02-17 17:40         ` Jakub Kicinski
2025-02-18  3:42           ` Herbert Xu
2025-02-18  7:41             ` Ard Biesheuvel
2025-02-18  8:02               ` Herbert Xu
2025-02-13 10:10   ` Ard Biesheuvel

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