numbers don't lie ...

[Dmitry Morozovsky]

On Wed, 20 Sep 2006, Eric Anderson wrote:

EA> >  >  > My experiments show that if you have enough memory to host radmdrive
EA> > for  > /usr/src you'd better leave it for caching - there were no
EA> > statistically
EA> >  > meaningful performance difference, at least on machines with 1G+ RAM.
EA> > 
EA> > That might only be true if you have enough RAM to keep
EA> > _all_ buildworld files (src, obj, toolchain) in the cache
EA> > _and_ you pre-read all of /usr/src before actually starting
EA> > the buildworld, so it is in the cache.  If you don't have
EA> > that much RAM, but enough to store /usr/src, then using
EA> > a RAM disk for it is a win.
EA> > 
EA> > Reading /usr/src from a physical disk certainly requires
EA> > quite some I/O that takes more than zero time.
EA> 
EA> But, in order to populate the ram disk, you must read /usr/src also from
EA> something, and that also takes time, which you should include in the full
EA> scope.

... and that populates cache with src files as well ;-)


Sincerely,
D.Marck                                     [DM5020, MCK-RIPE, DM3-RIPN]
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*** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck at rinet.ru ***
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