[PATCH] um: implement flush_cache_vmap/flush_cache_vunmap

[Anton Ivanov]

On 16/03/2021 08:55, Johannes Berg wrote:
> On Tue, 2021-03-16 at 08:46 +0000, Anton Ivanov wrote:
>>
>> Well spotted.
>>
>> Unless I am mistaken, there may be a slightly better way of doing it.
>>
>> We can implement arch_sync_kernel_mappings() and sync only where the
>> page modified mask says so by setting ARCH_PAGE_TABLE_SYNC_MASK
>>
>> This way flush_cache_* can remain nops as in asm-generic
> 
> Would that actually buy us anything?

It makes flushing conditional on a specific mask from the result of the mapping op. In theory, should be better. In practice - probably more of the same.

> 
> Not that I mind, or even understand the TLB code well, but it seems
> fairly similar?
> 
>> I am going to give that a spin, if it works, I will post it to the list by lunchtime GMT
> 
> Sounds good to me :)
> 
> I also made these patches:
> 
> https://lore.kernel.org/lkml/20210315235453.e3fbb86e99a0.I08a3ee6dbe47ea3e8024956083f162884a958e40@changeid/T/#u
> 
> 
> so my "vmalloc-heavy workload" no longer is vmalloc heavy since it now
> uses kvmalloc and never hits vmalloc, always kmalloc :)

:)

> 
> johannes
> 
> 
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-- 
Anton R. Ivanov
https://www.kot-begemot.co.uk/