[oe] Performance measurement: Building openembedded-core with and without overclocking on C-i7 2600K

[Roman Khimov]

В сообщении от 18 октября 2011 10:03:25 автор Ulf Samuelsson написал:
> Also what happens if it it built on a fast SSD, or even a RAMdisk?

Our main build server has two Xeons X5670 with 96 GB of RAM. It's running 24×7 
cyclicly doing clean isolated builds of all our OE projects (currently five). 
"Isolated" means that the the actual build is done inside a container (LXC) 
with no network available at all, that is a requirement for all our builds, to 
be able to take one tarball of sources, one tarball of OE tree and build the 
project somewhere in a nuclear bunker.

The system is configured in such way that container is located on tmpfs (with 
size of 50 GB). The most complex build takes about hour and a half on this 
system occupying about 45 GB of space in a ramdisk.

So today I tried to get some RAM vs. Linux cache statistics and switched this 
mount point over to newly created 60 GB LVM partition with ext4 on RAID0 array 
consisting of two SAS 15K drives.

The system made builds for three projects is this configuration and I see no 
difference at all, usual 1-2 minutes deviation. Granted, the system has quite 
powerful disks (RAID array gives about 380 MB/sec on hdparm) and things might 
be a little different on plain SATA drives, but frankly I'd expected to see 
the difference anyway since there are lots of small files involved in a build.

Maybe I should try to further degrade the disk system by creating some 
encrypted volume inside LVM, but still from what I see Linux caching and 
buffering works good enough, just give it as much RAM as you can.

But then also what you'll get from RAM or disk or even CPU upgrade depends on 
what type of build you have. Upgrading developers build servers from pair of 
4-core Opterons (don't remember exact model) with 8 GB of RAM to pair of Xeons 
E5620 with 24 GB of RAM with comparable disks gave about 20-30% of build time 
reduction for one project and 50% for another. But that builds are not 
isolated and use icecc cluster with all build servers available to the 
cluster, maybe that helps also in our situation.

-- 
 http://roman.khimov.ru
mailto: roman at khimov.ru
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