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Re: [Xen-devel] [Patch] don't spin with irq disabled
| To: | "Juergen Gross" <juergen.gross@xxxxxxxxxxxxxxxxxxx> |
|---|---|
| Subject: | Re: [Xen-devel] [Patch] don't spin with irq disabled |
| From: | "Jan Beulich" <jbeulich@xxxxxxxxxx> |
| Date: | Thu, 26 Mar 2009 12:23:14 +0000 |
| Cc: | "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx> |
| Delivery-date: | Thu, 26 Mar 2009 05:22:40 -0700 |
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| In-reply-to: | <49CB441E.9030006@xxxxxxxxxxxxxxxxxxx> |
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| Sender: | xen-devel-bounces@xxxxxxxxxxxxxxxxxxx |
>>> Juergen Gross <juergen.gross@xxxxxxxxxxxxxxxxxxx> 26.03.09 10:00 >>> >Attached patch reduces interrupt latency in lock handling. >spin_lock_irq and spin_lock_irqsave used to turn off IRQs and then tried to >get the lock. If the lock was already held, waiting for the lock was done with >IRQs still off. >The patch reenables IRQs during the wait loop. This is wrong - you must not enable interrupts if they weren't enabled upon entry to these two functions. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel |
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