On 2018-05-18 13:46:36 [+0100], Dave Martin wrote: > On Thu, May 17, 2018 at 07:19:43PM +0100, Dave Martin wrote: > > [...] > > > kernel_neon_begin() could then do > > > > local_fpsimd_context_lock(); > > > > /* ... */ > > > > preempt_disable(); > > local_unlock(fpsimd_context_lock); > > > > ... with the following in kernel_neon_end(): > > > > local_unlock(fpsimd_lock); > > preempt_enable(); > > > > > > If kernel-mode NEON was considered harmful to RT due to the context > > switch overheads, then the above might be overkill. SVE will be worse > > in that regard, and also needs thinking about at some point -- I've not > > looked at if from the RT angle at all. > > Hmmm, !KERNEL_MODE_NEON breaks EFI, so this probably does want looking > at. Ard's recent rework to enable voluntary preemption the crypto > backends for arm64 [1] should reduce the fpsimd_lock blackouts, but it > still depends on the backends playing nice.
oh. I've seen the series, I more or less asked for this and I am glad for it. I will try to unbreak this EFI problem then… I remember the good old days when the boot loader was gone after it jumped to the kernel… > Cheers > ---Dave Sebastian
