On Tue, 22 Dec 2009, Gregory Haskins wrote: > On 12/22/09 1:53 PM, Avi Kivity wrote: > > I asked why the irqfd/ioeventfd mechanisms are insufficient, and you did not reply. > > > > BTW: the ioeventfd issue just fell through the cracks, so sorry about > that. Note that I have no specific issue with irqfd ever since the > lockless IRQ injection code was added. > > ioeventfd turned out to be suboptimal for me in the fast path for two > reasons: > > 1) the underlying eventfd is called in atomic context. I had posted > patches to Davide to address that limitation, but I believe he rejected > them on the grounds that they are only relevant to KVM. I thought we addressed this already, in the few hundreds of email we exchanged back then :) > 2) it cannot retain the data field passed in the PIO. I wanted to have > one vector that could tell me what value was written, and this cannot be > expressed in ioeventfd. Like might have hinted in his reply, couldn't you add data support to the ioeventfd bits in KVM, instead of leaking them into mainline eventfd? - Davide -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
