multithreaded yum-presto Koji builds for F16 and F17

[Adam Pribyl]

On Thu, 11 Oct 2012, Andre Robatino wrote:

> Jonathan Dieter has just made F16 and F17 Koji builds for the multithreaded
> yum-presto (currently only in F18 and Rawhide) which takes advantage of multiple
> cores. Since applydeltarpm maxes out the CPU, they will probably give a linear
> speedup. He doesn't plan to ever put the F16 version into updates-testing but
> might do it for F17 if it gets positive feedback. (I personally don't have
> multicore hardware so can only test for good behavior, not for the speedup.)
>
> https://bugzilla.redhat.com/show_bug.cgi?id=701711#c10
>
> http://koji.fedoraproject.org/koji/buildinfo?buildID=359518
> (yum-presto-0.9.0-1.fc16)
>
> http://koji.fedoraproject.org/koji/buildinfo?buildID=359516 (um-presto-0.9.0-1.fc17)
>


I've tried that, but the speedup is invisible. It runs on both cores I 
have but the rebuild speed is same as old single threaded. If it runs on 
one core the build speed drops to half. This is on SSD so disk throughput 
is hardly a bottleneck.

To be honest - when I started to use presto few years ago, it was 
rebuilding packages at speed of 1MB/s. During years it slowly dropped to 
around 600kB/s. With this version it peaks around 900kB/s but average is 
still around 600kB/s, when only one applydeltarpm is runnig the rebuild 
drops to 200-300kB/s.
Thats what I see.

Adam Pribyl