On Thu, Aug 10, 2017 at 01:40:07PM +0100, Julien Grall wrote: > Hi Wei, > > On 10/08/17 12:40, Wei Liu wrote: > > On Thu, Aug 10, 2017 at 01:29:04PM +0530, Bhupinder Thakur wrote: > > > Hi Wei, > > > > > > On 9 August 2017 at 16:33, Wei Liu <wei.l...@citrix.com> wrote: > > > > On Wed, Aug 09, 2017 at 04:28:14PM +0530, Bhupinder Thakur wrote: > > > > > Hi Julien, > > > > > > > > > > Thanks for the testing. > > > > > > > > > > On 8 August 2017 at 21:29, Julien Grall <julien.gr...@arm.com> wrote: > > > > > > Hi Bhupinder, > > > > > > > > > > > > I gave another and I have a couple of comments. > > > > > > > > > > > > Booting Linux with earlycon enabled take quite a while. I can see > > > > > > the > > > > > > characters coming slower than on the minitel. It seems to be a bit > > > > > > better > > > > > > after switching off the bootconsole. Overall Linux is taking ~20 > > > > > > times to > > > > > > boot with pl011 vs HVC console. > > > > > > > > > > > > I do agree that pl011 is emulated and therefore you have to trap > > > > > > after each > > > > > > character. But 20 times sounds far too much. > > > > > > > > > > > I think this slowness could be due to ratelimiting of the pl011 events > > > > > in xenconosle. Currently, the rate limit is > > > > > set to 30 events per 200 msecs (see > > > > > RATE_LIMIT_ALLOWANCE/RATE_LIMIT_PERIOD). > > > > > > > > > > I increased the rate limit to 600 events (30 * 20) per 200 msecs. With > > > > > this change, > > > > > I see that the the find command is running faster and smoother. > > > > > Earlier the find output would be jerky. > > > > > > > > Please consider batching the events instead of bumping the limit. > > > > > > If I try to batch the events then it may delay per character > > > processing (if no further characters are coming) since we will wait > > > for more events to come to batch them together. By keeping the rate > > > limit high, it is ensured that it can handle large burst of events. If > > > there is sporadic data then the rate limit is not hit. > > > > But do you really need to send an event for every character (that's my > > reading of your patch, please correct me if I'm wrong)? Suppose you have > > a buffer you can send one event when the buffer is processed. > > I am not sure what you mean by buffer here. The interface with the guest is > a single data register. So characters are written one by one.
Yes, that's what the guest sees, but that is not necessarily what xenconsoled sees. > > > > > > > > > I am thinking of making the rate limit configuration per console. > > > > > > > There is the question why vuart is special with regard to other types of > > console. > > > > If something is mandated by the spec it should be specifically called > > out to justify the decision to bump the rate limit. > > I might have other ideas how to improve the speed. I will answer on > Bhupinder's e-mail. > Sure. > Cheers, > > -- > Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
