Messages in this thread | | | Subject | Re: [RFC PATCH] arm64/fpsimd: Don't disable softirq when touching FPSIMD/SVE state | From | Julien Grall <> | Date | Fri, 15 Mar 2019 10:22:43 +0000 |
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On 15/03/2019 10:06, Dave Martin wrote: > On Thu, Mar 14, 2019 at 06:07:19PM +0000, Julien Grall wrote: >> Hi Sebastian, >> >> On 3/4/19 5:25 PM, Sebastian Andrzej Siewior wrote: > > [...] > >>> It would increase the softirq latency but the question is how bad would >>> it be. It would continue once the SIMD section is done. >> >> On Arm, the kernel may use either FPSIMD or SVE (if supported by the >> platform). While the FPSIMD context is fairly small (~4K), the SVE context >> can be up to ~64KB. > > It's not quite as bad as that. The FPSIMD state is ~0.5K, with the SVE > state size being up to ~8.5K (though for today's implementations ~2K may > be considered typical).
Whoops, I forgot to divide by 8. Thank you for spotting it!
Cheers,
-- Julien Grall
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