Re: Fixing excessive shootdowns during FFS read (kern/53124) on x86 - emap, direct map

[Michael van Elst <mlelstv%serpens.de@localhost>]

On Fri, May 11, 2018 at 05:28:18PM +0200, Jaromír Dole?ek wrote:

> I've implemented a tweak to read-ahead code to skip the full
> read-ahead if last page of the range is already in cache, this
> improved things a lot:

That looks a bit like a hack. Can't you just call uvm_pagelookup()
to determine if the last page is cached? Or if that's too UVM internal,
call uvm_findpages() with UFP_NOALLOC.


Greetings,
-- 
                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."