VM idle page zeroing

Venkatesh Srinivas me at endeavour.zapto.org
Mon May 17 00:23:08 PDT 2010


On a 2.4 GHz P4 with 2GB of RAM - buildkernel took 1048 sec on a kernel 
immediately preceding the idlezero patch; on a kernel with the idlezero 
patch but with it disabled, 1054 sec; with idlezero on, 1051 sec; with
idlezero and nocache on, 1052 sec. So as to whether it improved 
performance, 'too close to call'.

In the non-idlezero and idlezero runs, there was ~6.5M zero-fill faults; 
less than 1% were ozfod (found a zero page available) in the former, 
approximately 40% in the latter. At various points during the build in the 
idlezero case, we just ran out of zero pages and it would be some time 
before they were restored.

Not sure what to make of this.
-- vs

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