multithreaded yum-presto Koji builds for F16 and F17

[drago01]

On Thu, Oct 11, 2012 at 8:28 PM, Adam Pribyl <pribyl at lowlevel.cz> wrote:
> 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.

Here it went up from 1.2MB/s to 2.1-2.6MB/s (4 cores - 8 threads). Not
sure how many threads it actually uses but this is not a linear
speedup. Disk is an SSD as well.