Manfred Spraul wrote:
> The scary part from the system perspective are the 35 million context
> switches that were generated by the BufMgrLock and the LockMgrLock. I
> remember there were patches that tried other algorithms instead of the
> simple LRU for the buffer manager. Has anyone tried to
Tom Lane wrote:
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.
Mark ran a DBT-2 testrun with the attached statistics patch applied: It
col
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
perh
Manfred Spraul <[EMAIL PROTECTED]> writes:
> My guess: Pentium 4 cpu support something like 250 uops in flight - it
> will have a dozend of the spinlock loops in it's pipeline. When the
> spinlock is released, it must figure out which of the loops should get
> it, and gets lost. My guess is that
L PROTECTED]>
> Subject: Re: [PATCHES] update i386 spinlock for hyperthreading
>
> Tom Lane wrote:
>
> >Manfred Spraul <[EMAIL PROTECTED]> writes:
> >
> >
> >>Tom Lane wrote:
> >>
> >>
> >>>Don't you have to put it in a spec
Tom Lane wrote:
Manfred Spraul <[EMAIL PROTECTED]> writes:
Tom Lane wrote:
Don't you have to put it in a specific place in the loop to make that
work? If not, why not?
Rep;nop is just a short delay - that's all.
That view seems to me to be directly contradicted by this stateme
Manfred Spraul <[EMAIL PROTECTED]> writes:
> Tom Lane wrote:
>> Don't you have to put it in a specific place in the loop to make that
>> work? If not, why not?
>>
> Rep;nop is just a short delay - that's all.
That view seems to me to be directly contradicted by this statement:
> The PAUSE instr
Tom Lane wrote:
Manfred Spraul <[EMAIL PROTECTED]> writes:
Intel recommends to add a special pause instruction into spinlock busy
loops. It's necessary for hyperthreading - without it, the cpu can't
figure out that a logical thread does no useful work and incorrectly
awards lots of execution
Manfred Spraul <[EMAIL PROTECTED]> writes:
> Intel recommends to add a special pause instruction into spinlock busy
> loops. It's necessary for hyperthreading - without it, the cpu can't
> figure out that a logical thread does no useful work and incorrectly
> awards lots of execution resources t
Hi,
Intel recommends to add a special pause instruction into spinlock busy
loops. It's necessary for hyperthreading - without it, the cpu can't
figure out that a logical thread does no useful work and incorrectly
awards lots of execution resources to that thread. Additionally, it's
supposed to
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