Re: clarification about redhat and vm

["Willi Nüßer" <wilhelm.nuesser@sap.com>]

Alan Cox wrote:
> 
> > "If redhat doesn't use the -aa VM " was a short form of "if redhat
> > cannot see the goodness of all the bugfixing work that happened between
> > the 2.4.9 VM and any current branch 2.4, and so if they keep shipping
> > 2.4.9 VM as the best one for DBMS and critical VM apps like the SAP
> > benchmark".
> 
> The RH VM is totally unrelated to the crap in 2.4.9 vanilla. The SAP comment
> begs a question. 2.4.10 seems to have problems remembering to actually
> do fsync()'s. How much of your SAP benchmark is from fsync's that dont
> happen ? Do you get the same values with 2.4.18-aa ?


Well, basically we checked the thing many times with quite different
kernels.
Our current tests - which show exactly the same results as
2.4.[10,14,15] - run
on the new "official" SuSE kernel 2.4.16.  Again, we  observe a
performance increase
in high swap situations of about a factor of ten compared to 2.4.[7,9].
 
IMO, this shows that errors like fsync etc. are _not_ responsible for
the improved
performance.  

But of course, we will check the newer kernels as well.  I think we
could live 
with another factor of ten ...



-- 
Best regards
Willi

-----------------------------------
Willi Nuesser
SAP Linuxlab