Messages in this thread |  | | Date | Sat, 22 Sep 2001 14:28:47 +0200 | From | Ralf Baechle <> | Subject | Re: Purpose of the mm/slab.c changes |
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On Sun, Sep 09, 2001 at 01:58:44PM -0700, Davide Libenzi wrote:
> >> Do You see it as a plus ? > >> The new allocated slab will be very likely written ( w/o regard > >> about the old content ) and an L2 mapping will generate > >> invalidate traffic. > > > > If your invalidates are slower than your RAM, you should > > consider getting another computer. > > You mean a Sun, that uses a separate bus for snooping ? :) > Besides to not under estimate the cache coherency traffic ( that on many CPUs > uses the main memory bus ) there's the fact that the old data eventually > present in L2 won't be used by the new slab user.
That's actually what having a slab cache of pre-initialized elements tries to achieve.
On anything that uses a MESI-like cache coherence protocol a cached dirty cache line that is written to will not cause any coherency traffic and thus be faster.
Ralf
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