[Intel-wired-lan] [PATCH RFC PKS/PMEM 22/58] fs/f2fs: Utilize new kmap_thread()
willy at infradead.org
Mon Oct 12 16:44:38 UTC 2020
On Mon, Oct 12, 2020 at 09:28:29AM -0700, Dave Hansen wrote:
> kmap_atomic() is always preferred over kmap()/kmap_thread().
> kmap_atomic() is _much_ more lightweight since its TLB invalidation is
> always CPU-local and never broadcast.
> So, basically, unless you *must* sleep while the mapping is in place,
> kmap_atomic() is preferred.
But kmap_atomic() disables preemption, so the _ideal_ interface would map
it only locally, then on preemption make it global. I don't even know
if that _can_ be done. But this email makes it seem like kmap_atomic()
has no downsides.
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