> But a better question is - why should this be done - especially from the guest > which has a limited view of the machine? The machine might be running a lot of > other requests so the OBFF inside the guest could be invalid. > Maybe I did not describe it clearly, the original idea is host admin can control the inode interface but not guest. > -----Original Message----- > From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@xxxxxxxxxx] > Sent: Saturday, April 07, 2012 2:40 AM > To: Hao, Xudong > Cc: linux-pci@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; > e1000-devel@xxxxxxxxxxxxxxxxxxxxx; Jesse Barnes > Subject: Re: Expose ltr/obff interface by sysfs > > On Fri, Apr 06, 2012 at 02:43:59AM +0000, Hao, Xudong wrote: > > Hi, > > > > I'm working on virtualization Xen/KVM. I saw there are ltr/obff > enabling/disabling function in pci.c, but no called till now. I want to know if > anybody(driver developer) are working for using it? Can driver change the LTR > latency value dynamically? > > > > /* > > LTR(Latency tolerance reporting) allows devices to send messages to the root > complex indicating their latency tolerance for snooped & unsnooped memory > transactions. > > OBFF (optimized buffer flush/fill), where supported, can help improve energy > efficiency by giving devices information about when interrupts and other > activity will have a reduced power impact. > > */ > > > > One way to control ltr/obff is used by driver, however, I'm considering that in > virtualization, how guest OS driver control them. I have an idea that expose an > inode interface by sysfs, like "reset" inode implemented in pci-sysfs.c, so that > system user/administrator can enable/disable ltr/obff or set latency value on > userspace, but not limited on driver. Comments? > > So right now the driver inside the guest can probably see it, but can't change > them. > (As those requests end up being filtered). > > But there is nothing wrong with your changing those values from within the > host. > > But a better question is - why should this be done - especially from the guest > which has a limited view of the machine? The machine might be running a lot of > other requests so the OBFF inside the guest could be invalid. > > > > > > < pls CC me when reply this mail, thanks > > > > > Best Regards, > > Xudong Hao > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-pci" > > in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo > > info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
