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Re: [Xen-devel] [PATCH] Add SCHEDOP_block_on
On 15 Mar 2006, at 23:58, Ryan wrote:
I'm not 100% sure, but I believe that jiffies does not get updated while interrupts are disabled (the timer is an interrupt in a domU, right?). Icould never verify from the source if this is the case, but if the pcibackend disappears or stops responding while the pci frontend is waitingfor an operation to complete, this could be a problem for the new code in pcifront. I've been preparing my patch for late binding in the pcibackend and if I unload the pci backend module (yes, unloading will workwith my patch!), the pci frontend domain appears to hang (inside of thewhile loop in do_pci_op()) whereas prior to the HYPERVISOR_poll call andjiffies check, the ttl would count down to 0 and error out of the spinand clean-up gracefully. I chose my ttl method over jiffies in the firstplace because of this problem with jiffies not getting updated. What would be the best way to fix this problem? The ttl method I had is not that elegant...
Yes, you make a very good point about using jiffies. I've checked in a fix to use gettimeofday instead, which does continue to work even with interrupts disabled.
Also, the timeout of 5s is arbitrary. We could make it rather less if you think that makes sense.
-- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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