Re: update i386 spinlock for hyperthreading

Tom Lane wrote:

>Anyway, I've committed your patch with some changes.
>
>
Thanks.

>BTW, I noticed a lot of concern in the Intel app notes about reserving
>64 or even 128 bytes for each spinlock to avoid cache line conflicts.
>That seems excessive to me (we use a lot of spinlocks for buffers), but
>perhaps it is worth looking into.
>
This recommendation usually ignored in the Linux kernel.  A few very hot
spinlocks have an exclusive cacheline, but most don't.

>>Is there an easy way find out which LWLock is contended?
>>
>>
>
>Not from oprofile output, as far as I can think.  I've suspected for
>some time that the BufMgrLock is a major bottleneck, but have no proof.
>
>
I'll try to write a patch that dumps the LWLock usage and ask mark to
run it.

--
    Manfred