In UP machines Spinlocks are compiled away, so that it only disables interrupts
on spin_lock_irqsave and enables interrupts on spin_lock_irqrestore. This
protects the critical section the code executing in process context and
interrupt routine. Pls correct me if I am wrong.
Rajendra Stalekar <[EMAIL PROTECTED]> wrote: v\:*
{behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:*
{behavior:url(#default#VML);} .shape {behavior:url(#default#VML);}
st1\:*{behavior:url(#default#ieooui) }
---------------------------------
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of
jiayinjia1983116
Sent: Thursday, September 20, 2007 11:06 AM
To: Mansha Linux
Cc: [email protected]
Subject: Re:Spinlocks on Uniprocessor
As for as I know,when process/Thread is in runqueue,then may have allocate
some resource even they do not running right now,In order to keep the data
consistent(can not be modified by other processes/threads) ,we should use
spinlock to protect the data.
[rajendra stalekar] > I think that the code protected by spinlock must
never have a blocking call(eg. copy_to_user, copy_from_user, read, write etc),
whenever a thread acquires a spinlock whatever the critical section code has to
be asynchronous and yes of course kernel must be pre-emptible.
ÔÚ2007-09-19£¬"Mansha Linux" <[EMAIL PROTECTED]> £º
Hi all,
Could you please explain me why do we need the spinlocks on uniprocessor
machines?
Is this the only reason that the kernel is preemptive ?
--
regards,
Mansha
---------------------------------
ɱ70ÍòÖÖľÂí²¡¶¾£¬ÈðÐÇ2008°æÃâ·Ñ
http://www.patni.com
World-Wide Partnerships. World-Class Solutions.
_____________________________________________________________________
This e-mail message may contain proprietary, confidential or legally privileged
information for the sole use of the person or entity to whom this message was
originally addressed. Any review, e-transmission dissemination or other use of
or taking of any action in reliance upon this information by persons or
entities other than the intended recipient is prohibited. If you have received
this e-mail in error kindly delete this e-mail from your records. If it appears
that this mail has been forwarded to you without proper authority, please
notify us immediately at [EMAIL PROTECTED] and delete this mail.
_____________________________________________________________________
---------------------------------
Tonight's top picks. What will you watch tonight? Preview the hottest shows on
Yahoo! TV.
