when startup delays become bugs

[Eric Sandeen]

On 5/17/13 5:39 PM, Chris Murphy wrote:
> 
> On May 17, 2013, at 3:53 PM, Eric Sandeen <sandeen at redhat.com> wrote:
> 
>>>> On Thu, 16.05.13 12:20, Chris Murphy (lists at colorremedies.com) wrote:
>>>>
>>>>> There have been no crashes, so ext4 doesn't need fsck on every boot:
>>>>>
>>>>>           4.051s systemd-fsck-root.service
>>>>>            515ms
>>>>>            systemd-fsck at dev-disk-by\x2duuid-09c66d01\x2d8126\x2d39c2\x2db7b8\x2d25f14cbd35af.service
> 
> 
>> When it took 4s above, was that a from a clean reboot (i.e. was the journal dirty?)
> 
> Clean. And it's a new file system, created within the hour of the time test. I also don't understand why there are two instances. There's only one ext4 file system on the computer.

Can't imagine why it takes 4s then, need finer-grained tracing I guess...

If I "e2fsck" a clean fs here it takes about 0.1s.

Most of its time is spent in read(); several reads get about 100k of data from the device, and that's about it.

As a sanity check I suppose you could try e2fsck from a rescue environment and see if it still takes that long, or of there is other overhead / interaction slowing it down.

-Eric

> 
> Chris Murphy
>