Re: [PATCH] udevd: fix WAIT_FOR_SYSFS

[Alan Jenkins <alan-jenkins@tuffmail.co.uk>]

Kay Sievers wrote:
> On Thu, Oct 23, 2008 at 21:56, Alan Jenkins <alan-jenkins@tuffmail.co.uk> wrote:
>   
>> Kay Sievers wrote:
>>     
>>> On Thu, Oct 23, 2008 at 21:03, Kay Sievers <kay.sievers@vrfy.org> wrote:
>>>       
>>>> On Thu, Oct 23, 2008 at 20:37, Alan Jenkins <alan-jenkins@tuffmail.co.uk> wrote:
>>>>
>>>>         
>>>>> The wait should be ordered after matching KERNEL, ENV, etc.
>>>>> but before ATTR.
>>>>>
>>>>> Without this, WAIT_FOR_SYSFS rules will be applied unconditionally
>>>>> to all events.
>>>>>
>>>>>           
>>>> Ah, nice! Thanks for finding that out. I do not have any of theses
>>>> rules left, as there are currently no know issues with recent kernels.
>>>> :) Applied.
>>>>         
>>> Oh, now that I expect it works for you without the long delay. :) How
>>> does is compare? Is it still slower?
>>>       
>
>   
>> No, that fixed it.  The network interface rename problem seems to have
>> gone as well (!).
>>
>> I just tested it on my desktop.  oprofile says it now _reduces_ cpu
>> cycles in udevd by 10%.  Not big enough to show up in time(1), but not
>> bad!  And it should help more on the EeePC, which has a less lavish cpu
>> cache.
>>     
>
> Sounds good. I've changed a few other things, which might make things faster:
>
> We cache the results of getpwnam/getgrnam() during rules parse time,
> some of the rules files I have here have ~700 rules with GROUP="..."
> keys ...
>
> We check at parse time, if we need to call fnmatch() for a key, or can
> just go with the much cheaper strcmp(). That seems to make a real
> difference with the large rules files I have.
>   

Nice.

> Also the snprintf() that was used compose the buffer to pass the event
> to a socket was _very_ expensive. We just use strlcpy() now and cache
> the result for the next RUN+="socket:" call.
>   

I might adapt that for udev-exec.

But I think it needs a flag like envp_uptodate, no?

Regards
Alan