Fine-grained locking for POSIX local sockets (UNIX domain sockets)

Robert Watson rwatson at
Mon May 8 07:35:13 UTC 2006

On Mon, 8 May 2006, Kris Kennaway wrote:

> unp contention has risen a bit.  The other big gain is to sleep mtxpool 
> contention, which roughly doubled:

In the general case, you can increase the size of the mutex pool.  However, 
since this is per-uid for the socket buffer resource limits, that won't help 
you as the same user will always contend with itself.  We'll need to think 
about this some -- good activity for the plane today :-).

Nice work so far, btw.  Sounds like we're making real headway!

Robert N M Watson

> /*
> * Change the total socket buffer size a user has used.
> */
> int
> chgsbsize(uip, hiwat, to, max)
>        struct  uidinfo *uip;
>        u_int  *hiwat;
>        u_int   to;
>        rlim_t  max;
> {
>        rlim_t new;
>        UIDINFO_LOCK(uip);
> So the next question is how can that be optimized?
> Kris

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