Messages in this thread | | | Date | Sun, 26 Jun 2005 15:31:02 -0300 | From | Marcelo Tosatti <> | Subject | Re: increased translation cache footprint in v2.6 |
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On Mon, Jun 27, 2005 at 09:42:52AM +1000, Paul Mackerras wrote: > Marcelo Tosatti writes: > > > We've noticed a slowdown while moving from v2.4 to v2.6 on a small PPC platform > > (855T CPU running at 48Mhz, containing pair of separate I/D TLB caches with > > 32 entries each), with a relatively recent kernel (v2.6.11). > > > > Test in question is a "dd" copying 16MB from /dev/zero to RAMDISK. > > > > Pinning an 8Mbyte TLB entry at KERNELBASE brought performance back to v2.4 levels. > > Why are we not pinning a large TLB entry at KERNELBASE in 2.6? Was > that taken out to reduce the size of the tlb miss handler or > something?
Paul,
There are buggy instances of tlbie() destroying the 8Mbyte TLB entry - this is going to be fixed soon (its MPC8xx specific...)
I worry about machines who can't pin and/or smaller number of TLB entries.
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