passwd and pw speed regression?

Stefan Esser se at freebsd.org
Thu Feb 11 16:04:17 UTC 2016


Am 11.02.2016 um 16:02 schrieb Mike Tancsa:
> I noticed that on a new RELENG_10 box we are building, password updates
> are taking a very long time to build.  On the old RELENG_8 box, doing
> something simple like adding a user
> 
> # time pw useradd test12345
> 0.062u 0.063s 0:00.14 85.7%     54+988k 196+134io 0pf+0w
> 
> # time pw userdel test12345
> 0.164u 0.044s 0:00.20 100.0%    28+1181k 0+18io 0pf+0w
> 
> 
> On the new RELENG_10 box,
> 
> # time pw useradd test12345
> 0.060u 0.120s 0:58.89 0.3%      58+146k 12+6485io 0pf+0w
> 
> # time pw userdel test12345
> 0.125u 0.133s 0:58.80 0.4% 46+214k 13+9326io 0pf+0w
> 
> 
> # wc /etc/passwd
>     6113   14792  376128 /etc/passwd
> 
> 
> Yes, almost 60 seconds to add a user to the password file?
> 
> Does anyone know what is going on to account for the large difference
> and how to work around it ?  I am guessing

You are affected by the problem mentioned in

	https://reviews.freebsd.org/D5186

The output file is written with O_SYNC a record at a time
and this is slow (100 to 200 records per second on a non-SSD
drive).

This will be fixed in -CURRENT soon and I think the fix
should qualify for inclusion in the next 10-BETA, thereafter.

Regards, STefan

> https://svnweb.freebsd.org/base?view=revision&revision=285205
> 
> is the issue. Apart from keeping local source code changes, is there not
> a better way to not have reasonable speeds ?
> 
> 	---Mike



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