Samba and spinlocks on Linux (was Re: REPOST: Meaning of "tdb_free: left read failed at ...?"

Volker Lendecke Volker.Lendecke at SerNet.DE
Wed Feb 5 10:50:50 GMT 2003

On Wed, Feb 05, 2003 at 10:21:15AM +0100, Ralf G. R. Bergs wrote:
> I guess I should have defined CONFIG_RWSEM_GENERIC_SPINLOCK when compiling my 
> kernel since I also configured Samba with "--with-spinlocks":

Ok, this might explain it. Spinlocks are definitely a less tested part of the
code. I have never really activated them. At least under Linux fnctl locks
should be fast enough to cope with nearly any load.

> Would you recommend that I recompile the kernel to enable spinlock support 
> (since this is a two-way SMP machine), or would you rather recommend that I 
> don't use spinlocks (i.e. recompile Samba NOT to try to use spinlocks)?

The difference is that without Samba support for spinlocks you get another
round-trip into the kernel for each lock. Linux is quite fast with that, so if
you do not have a *very* good reason to enable them, could you please retry
without spinlocks?


P.S: I might be wrong, but I'm not sure whether the spinlock code ever actually
worked. Jeremy?

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