On Thu, 2015-09-24 at 11:41 +0000, David Laight wrote: > From: Christophe Leroy > > Sent: 22 September 2015 17:51 > ... > > Traditionaly, each driver manages one computer board which has its > > own components with its own memory maps. > > But on embedded chips like the MPC8xx, the SOC has all registers > > located in the same IO area. > > > > When looking at ioremaps done during startup, we see that > > many drivers are re-mapping small parts of the IMMR for their own use > > and all those small pieces gets their own 4k page, amplifying the > > number of TLB misses: in our system we get 0xff000000 mapped 31 times > > and 0xff003000 mapped 9 times. > > Isn't this a more general problem? > > If there are multiple remap requests for the same physical page > shouldn't the kernel be just increasing a reference count somewhere > and returning address in the same virtual page? > This should probably happen regardless of the address. > I presume it must be done for cacheable mappings.
Why would you assume that? -Scott _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
