[systemd-devel] readahead-replay seems to not be doing anything.

Kok, Auke-jan H auke-jan.h.kok at intel.com
Tue Feb 12 21:22:31 PST 2013

On Tue, Feb 12, 2013 at 6:29 PM, Lennart Poettering
<lennart at poettering.net> wrote:
> On Mon, 11.02.13 12:34, Gary van der Merwe (garyvdm at gmail.com) wrote:
>> This is my first post to this list, so I just want to say I thank you
>> too all those
>> who wrote systemd.
>> systemd-readahead-replay does not seem to be doing what it should.
>> Bootchart with readahead-[replay|collect] enabled:
>>   http://www.garyvdm.co.za/bootchart-20130211-1328.svg
> You are aware that you need to boot at least twice after removing the
> readahead file before measuring anything like this?

looking at the graph, there are 2 systemd-reada[snip] processes
showing up, which are the replay and collector threads - so from a
first glance, the replay thread is running and spending quite some
time (10+ seconds) doing stuff

if he had no /.readahead file, it would exit immediately... so I think
there's an actual problem here.

> It might be nice of bootchart would draw the IO utilization per-process
> into the bar. That way we could directly see how much IO it actually
> generates...

it's been on my wish list for a while, but I've not had time to figure
out if we can get this cheaply... should make some time to dig into


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