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From: Eric Biggers <ebiggers@kernel.org>
To: Andy Chiu <andy.chiu@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>,
	linux-riscv@lists.infradead.org, paul.walmsley@sifive.com,
	greentime.hu@sifive.com, guoren@linux.alibaba.com,
	bjorn@kernel.org, charlie@rivosinc.com, ardb@kernel.org,
	arnd@arndb.de, peterz@infradead.org, tglx@linutronix.de,
	Albert Ou <aou@eecs.berkeley.edu>
Subject: Re: [v9, 00/10] riscv: support kernel-mode Vector
Date: Sun, 7 Jan 2024 19:52:09 -0800	[thread overview]
Message-ID: <20240108035209.GA212605@sol.localdomain> (raw)
In-Reply-To: <CABgGipUgQS85P-PDRg9CF8LW6=VRfUVz_GJ4pZTfQN8gpB+-qA@mail.gmail.com>

On Mon, Jan 08, 2024 at 11:16:27AM +0800, Andy Chiu wrote:
> On Sat, Jan 6, 2024 at 2:59 AM Eric Biggers <ebiggers@kernel.org> wrote:
> >
> > Hi Palmer,
> >
> > On Fri, Dec 29, 2023 at 02:36:17PM +0000, Andy Chiu wrote:
> > > This series provides support running Vector in kernel mode.
> >
> > Is there any chance that you can take patches 1 and 2 of this series via the
> > RISC-V tree for v6.8?  The vector crypto patchset depends on those two patches.
> 
> Patch 4 is very essential for non-preemptible kernel-mode Vector,
> unless we want to bear restoring overhead at each kernel_vector_end().
> It's ~200 cycles on a VLEN=128 hardware. It happens as long as Vector
> is also used in user-mode, which will be very common. Please consider
> including up to patch 4 if we must split.
> 

It's definitely an important optimization, but I wouldn't call it "very
essential".  x86 didn't implement lazy restores until kernel v5.2.

My hope is that we can just get enough merged soon to unblock the vector crypto
patchset, which just needs kernel_vector_{begin,end} with softirq support.  The
remaining core vector work can happen in parallel.

- Eric

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  reply	other threads:[~2024-01-08  3:52 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-29 14:36 [v9, 00/10] riscv: support kernel-mode Vector Andy Chiu
2023-12-29 14:36 ` [v9, 01/10] riscv: Add support for kernel mode vector Andy Chiu
2023-12-30  1:05   ` Eric Biggers
2023-12-29 14:36 ` [v9, 02/10] riscv: vector: make Vector always available for softirq context Andy Chiu
2023-12-30  1:07   ` Eric Biggers
2023-12-29 14:36 ` [v9, 03/10] riscv: Add vector extension XOR implementation Andy Chiu
2023-12-29 14:36 ` [v9, 04/10] riscv: sched: defer restoring Vector context for user Andy Chiu
2023-12-29 14:36 ` [v9, 05/10] riscv: lib: vectorize copy_to_user/copy_from_user Andy Chiu
2023-12-29 14:36 ` [v9, 06/10] riscv: fpu: drop SR_SD bit checking Andy Chiu
2024-01-04  9:00   ` Song Shuai
2024-01-04 12:34   ` Guo Ren
2023-12-29 14:36 ` [v9, 07/10] riscv: vector: do not pass task_struct into riscv_v_vstate_{save,restore}() Andy Chiu
2023-12-29 14:36 ` [v9, 08/10] riscv: vector: use a mask to write vstate_ctrl Andy Chiu
2023-12-29 14:36 ` [v9, 09/10] riscv: vector: use kmem_cache to manage vector context Andy Chiu
2023-12-29 14:36 ` [v9, 10/10] riscv: vector: allow kernel-mode Vector with preemption Andy Chiu
2024-01-04 15:02   ` Wang, Xiao W
2024-01-10 15:31     ` Andy Chiu
2024-01-11 13:26       ` Andy Chiu
2024-01-05 18:59 ` [v9, 00/10] riscv: support kernel-mode Vector Eric Biggers
2024-01-08  3:16   ` Andy Chiu
2024-01-08  3:52     ` Eric Biggers [this message]
2024-01-10 15:02       ` Palmer Dabbelt

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