From: Richard Henderson <richard.henderson@linaro.org>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-devel@nongnu.org, qemu-arm@nongnu.org, gustavo.romero@linaro.org
Subject: Re: [PATCH v2 1/6] linux-user/aarch64: Extend PR_SET_TAGGED_ADDR_CTRL for FEAT_MTE3
Date: Wed, 7 Feb 2024 10:31:42 +1000 [thread overview]
Message-ID: <d57a4146-d7f5-4ba1-a11f-67e51d407423@linaro.org> (raw)
In-Reply-To: <CAFEAcA8AuQZNbT=7WFXVPDzDywPPp1YZ=Bkow7Dgq2pC9=9X-g@mail.gmail.com>
On 2/7/24 00:23, Peter Maydell wrote:
> On Tue, 6 Feb 2024 at 03:06, Richard Henderson
> <richard.henderson@linaro.org> wrote:
>>
>> When MTE3 is supported, the kernel maps
>> PR_MTE_TCF_ASYNC | PR_MTE_TCF_SYNC
>> to
>> MTE_CTRL_TCF_ASYMM
>> and from there to
>> SCTLR_EL1.TCF0 = 3
>
> This depends on the setting of
> /sys/devices/system/cpu/cpu<N>/mte_tcf_preferred :
> I think you only get asymm here if the sysadmin has set
> mte_tcf_preferred to 'asymm'; the default is 'async'.
Hmm, I missed that somewhere in the rat's nest.
I suspect this is over-engineered, such that no one will understand how to use it.
> For QEMU's implementation, are there any particular
> performance differences between sync, async and asymm ?
I doubt it. Getting to the error path at all is the bulk of the work.
I think "performance" in this case would be highly test-case-centric.
Does the test "perform better" with async, which would allow the entire vector operation
to finish in one go?
I suspect that for debugging purposes, sync is always preferred.
That might be the best setting for qemu.
r~
next prev parent reply other threads:[~2024-02-07 0:32 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-06 3:05 [PATCH v2 0/6] target/arm: assorted mte fixes Richard Henderson
2024-02-06 3:05 ` [PATCH v2 1/6] linux-user/aarch64: Extend PR_SET_TAGGED_ADDR_CTRL for FEAT_MTE3 Richard Henderson
2024-02-06 14:23 ` Peter Maydell
2024-02-07 0:31 ` Richard Henderson [this message]
2024-02-07 2:10 ` Richard Henderson
2024-02-06 15:18 ` Gustavo Romero
2024-02-06 3:05 ` [PATCH v2 2/6] target/arm: Fix nregs computation in do_ld_zpa Richard Henderson
2024-02-06 14:46 ` Peter Maydell
2024-02-07 0:42 ` Richard Henderson
2024-02-06 3:05 ` [PATCH v2 3/6] target/arm: Adjust and validate mtedesc sizem1 Richard Henderson
2024-02-06 14:49 ` Peter Maydell
2024-02-06 3:05 ` [PATCH v2 4/6] target/arm: Split out make_svemte_desc Richard Henderson
2024-02-06 14:52 ` Peter Maydell
2024-02-06 3:05 ` [PATCH v2 5/6] target/arm: Handle mte in do_ldrq, do_ldro Richard Henderson
2024-02-06 14:53 ` Peter Maydell
2024-02-06 3:05 ` [PATCH v2 6/6] target/arm: Fix SVE/SME gross MTE suppression checks Richard Henderson
2024-02-06 14:54 ` Peter Maydell
2024-02-06 14:54 ` [PATCH v2 0/6] target/arm: assorted mte fixes Peter Maydell
2024-02-06 20:10 ` Richard Henderson
2024-02-06 15:17 ` Gustavo Romero
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