[yocto] Build time data

[Koen Kooi]

Op 13 apr. 2012, om 10:45 heeft Richard Purdie het volgende geschreven:

> On Thu, 2012-04-12 at 07:34 -0700, Darren Hart wrote:
>> 
>> On 04/12/2012 07:08 AM, Björn Stenberg wrote:
>>> Darren Hart wrote:
>>>> /dev/md0        /build          ext4 
>>>> noauto,noatime,nodiratime,commit=6000
>>> 
>>> A minor detail: 'nodiratime' is a subset of 'noatime', so there is no
>>> need to specify both.
>> 
>> Excellent, thanks for the tip.
> 
> Note the key here is that for a system with large amounts of memory, you
> can effectively keep the build in memory due to the long commit time.
> 
> All the tests I've done show we are not IO bound anyway.

Consider this scenario:

OS disk on spinning rust (sda1, /)
BUILDDIR on spinning rust (sdb1, /OE)
WORKDIR on SSD (sdc1, /OE/build/tmp/work)
SD card in USB reader (sde1)

When I do the following during a build all CPUs will enter IO wait and the build grinds to a halt:

cd /media ; xz -d -c foo.img.xz | pv -s 3488M > /dev/sde

That only touches the OS disk and the SD card, but for some reason the 3.2.8 kernel stops IO to the OE disks as well. do_patch for my kernel recipe has been taking more than an hour now, it usually completes in less than 5 minutes (a few hundred patches applied with a custom patcher, git-am).

regards,

Koen