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). For comparision, I believe AVX-512 has ~2K of state. Cheers ---Dave
