[systemd-devel] Improve boot-time of systemd

[fykcee1 at gmail.com]

2011/3/29 Lennart Poettering <lennart at poettering.net>:
>> > On Sun, 20.03.11 05:28, fykcee1 at gmail.com (fykcee1 at gmail.com) wrote:
>> >> Current readahead implementation has some problems:
>> >> 1. It can't separate *real* block read requests from all read
>> >> requests(which includes more blocks read by the kernel's readahead
>> >> logic)
I guess we need to add the following in systemd-readahead-collect.service:
ConditionPathExists=!/.readahead

Replayed blocks will always be collected, but in the case of
enable/disable/install/remove services, read actions relating to
removed/disabled services need't be collected.

Each time we enable/disable/install/remove services, /.readahead
should be removed.


> The idea of readahead is to load as much IO requests into the kernel as
> possible, so that the IO elevator can decide what to read when and to
> reorder things as it likes and thinks is best.
>
Well, this actually makes some early services waiting for I/O, then
the whole boot process blocks. See the attachment.



-- 
Regards,
- cee1
-------------- next part --------------
A non-text attachment was scrubbed...
Name: noreplay-vs-replay.png
Type: image/png
Size: 122308 bytes
Desc: not available
URL: <http://lists.freedesktop.org/archives/systemd-devel/attachments/20110330/227ed3cf/attachment-0001.png>