cvs commit: src/sys/kern vfs_bio.c

[Jeff Roberson]

On Fri, 21 Mar 2008, Poul-Henning Kamp wrote:

> In message <200803211000.m2LA05KN096467 at repoman.freebsd.org>, Jeff Roberson wri
> tes:
>> jeff        2008-03-21 10:00:05 UTC
>>
>>  FreeBSD src repository
>>
>>  Modified files:
>>    sys/kern             vfs_bio.c
>>  Log:
>>   - Reduce contention on the global bdonelock and bpinlock by using
>>     a pool mutex to protect these sleep/wakeup/counter races.  This
>>     still is preferable to bloating each bio with a mtx.
>
> Shouldn't this be the BOLOCK ?

As mentioned on irc;  I believe these originally were not done this way 
because we may have a buf without a bufobj.  I think that happens when we 
use a pager buf for physio.

The other reason not to do that would be to attempt to reduce contention 
on the bo lock which is increasingly becoming a problem.  Patches are 
underway to address that.

Thanks,
Jeff

>
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
>