Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-10-06 Thread Stefano Stabellini
On Tue, 6 Oct 2015, Roger Pau Monné wrote: > Do KVM guests also need such extensive set of modifications in order to > run using 64KB pages? I know it's not fair to compare KVM and Xen in > this regard, because the interfaces are very different, but that's what > developers are going to look at. Q

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-10-06 Thread Ian Campbell
On Tue, 2015-10-06 at 11:28 +0200, Roger Pau Monné wrote: > El 22/09/15 a les 12.59, Ian Campbell ha escrit: > > On Mon, 2015-09-14 at 17:23 +0200, Roger Pau Monné wrote: > > > I'm not saying that we shouldn't take those patches, I'm just saying > > > that IMHO this is a workaround, and I would lik

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-10-06 Thread Roger Pau Monné
El 22/09/15 a les 12.59, Ian Campbell ha escrit: > On Mon, 2015-09-14 at 17:23 +0200, Roger Pau Monné wrote: >> I'm not saying that we shouldn't take those patches, I'm just saying >> that IMHO this is a workaround, and I would like to see a plan and >> somebody committed to have it fixed in a prop

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-29 Thread David Vrabel
On 29/09/15 17:33, Julien Grall wrote: > Hi David, > > On 29/09/15 17:27, David Vrabel wrote: >> On 07/09/15 16:33, Julien Grall wrote: >>> >>> A branch based on the latest xentip/for-linus-4.3 can be found here: >>> >>> git://xenbits.xen.org/people/julieng/linux-arm.git branch xen-64k-v4 >> >> Th

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-29 Thread Julien Grall
Hi David, On 29/09/15 17:27, David Vrabel wrote: > On 07/09/15 16:33, Julien Grall wrote: >> >> A branch based on the latest xentip/for-linus-4.3 can be found here: >> >> git://xenbits.xen.org/people/julieng/linux-arm.git branch xen-64k-v4 > > This has too many conflicts with the > git://git.kern

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-29 Thread David Vrabel
On 07/09/15 16:33, Julien Grall wrote: > > A branch based on the latest xentip/for-linus-4.3 can be found here: > > git://xenbits.xen.org/people/julieng/linux-arm.git branch xen-64k-v4 This has too many conflicts with the git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip.git for-linus-4.4 br

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-22 Thread Ian Campbell
On Mon, 2015-09-14 at 17:23 +0200, Roger Pau Monné wrote: > I'm not saying that we shouldn't take those patches, I'm just saying > that IMHO this is a workaround, and I would like to see a plan and > somebody committed to have it fixed in a proper way, by introducing a > 64KB PV block protocol. In

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-18 Thread Julien Grall
Hi Roger, On 14/09/15 13:08, Roger Pau Monné wrote: > Well, absolute numbers together with the standard deviation are IMHO the > best way to provide those figures (ie: see ministat(1) output for > example), but percentages should also be fine. > > I'm just interested in knowing the performance di

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-15 Thread Arnd Bergmann
On Tuesday 15 September 2015 14:14:09 David Vrabel wrote: > On 14/09/15 12:32, Arnd Bergmann wrote: > > On Monday 14 September 2015 13:04:59 Roger Pau Monné wrote: > >>> TBH, I'm expecting a small impact to the performance. It would be hard > >>> to get the exactly the same performance as today if

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-15 Thread David Vrabel
On 14/09/15 12:32, Arnd Bergmann wrote: > On Monday 14 September 2015 13:04:59 Roger Pau Monné wrote: >>> TBH, I'm expecting a small impact to the performance. It would be hard >>> to get the exactly the same performance as today if we keep the helpers >>> to avoid the backend dealing himself with

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-14 Thread Roger Pau Monné
El 14/09/15 a les 16.54, Stefano Stabellini ha escrit: > On Mon, 14 Sep 2015, Roger Pau Monné wrote: >> IMHO this splitting is just a workaround for the fact that we don't have >> a 64KB PV block protocol, and this is the real problem that should be >> solved. > > 64K is a pure one guest kernel co

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-14 Thread Stefano Stabellini
On Mon, 14 Sep 2015, Roger Pau Monné wrote: > IMHO this splitting is just a workaround for the fact that we don't have > a 64KB PV block protocol, and this is the real problem that should be > solved. 64K is a pure one guest kernel configuration option, not a platform wide option. The hypervisor i

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-14 Thread Julien Grall
On 14/09/15 15:29, Roger Pau Monné wrote: >> To give you an example, Centos 7, which will support Xen and only 64KB >> page granularity, will be supported for years. Dropping any splitting in >> a short future (3-5 years) will just break those guests to boot on Xen. > > Can't the patches to suppor

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-14 Thread Roger Pau Monné
Hello, El 14/09/15 a les 14.47, Julien Grall ha escrit: > On 14/09/15 13:08, Roger Pau Monné wrote: >>> I'd like to see a basic support of 64KB page granularity upstream before >>> starting to think about performance improvement. And there is still a >>> lot to do. >> >> I wasn't actually thinking

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-14 Thread Julien Grall
On 14/09/15 13:08, Roger Pau Monné wrote: >> I'd like to see a basic support of 64KB page granularity upstream before >> starting to think about performance improvement. And there is still a >> lot to do. > > I wasn't actually thinking of this as a performance improvement, but > rather as a way of

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-14 Thread Roger Pau Monné
El 14/09/15 a les 13.21, Julien Grall ha escrit: > On 14/09/15 12:04, Roger Pau Monné wrote: >> Hello, >> >> El 14/09/15 a les 12.40, Julien Grall ha escrit: >>> Hi Roger, >>> >>> On 14/09/15 09:56, Roger Pau Monné wrote: El 07/09/15 a les 17.33, Julien Grall ha escrit: > Hi all, > >>>

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-14 Thread Arnd Bergmann
On Monday 14 September 2015 13:04:59 Roger Pau Monné wrote: > > TBH, I'm expecting a small impact to the performance. It would be hard > > to get the exactly the same performance as today if we keep the helpers > > to avoid the backend dealing himself with the splitting and page > > granularity. >

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-14 Thread Julien Grall
On 14/09/15 12:04, Roger Pau Monné wrote: > Hello, > > El 14/09/15 a les 12.40, Julien Grall ha escrit: >> Hi Roger, >> >> On 14/09/15 09:56, Roger Pau Monné wrote: >>> El 07/09/15 a les 17.33, Julien Grall ha escrit: Hi all, ARM64 Linux is supporting both 4KB and 64KB page granular

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-14 Thread Roger Pau Monné
Hello, El 14/09/15 a les 12.40, Julien Grall ha escrit: > Hi Roger, > > On 14/09/15 09:56, Roger Pau Monné wrote: >> El 07/09/15 a les 17.33, Julien Grall ha escrit: >>> Hi all, >>> >>> ARM64 Linux is supporting both 4KB and 64KB page granularity. Although, Xen >>> hypercall interface and PV prot

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-14 Thread Julien Grall
Hi Roger, On 14/09/15 09:56, Roger Pau Monné wrote: > El 07/09/15 a les 17.33, Julien Grall ha escrit: >> Hi all, >> >> ARM64 Linux is supporting both 4KB and 64KB page granularity. Although, Xen >> hypercall interface and PV protocol are always based on 4KB page granularity. >> >> Any attempt to

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-14 Thread Roger Pau Monné
El 07/09/15 a les 17.33, Julien Grall ha escrit: > Hi all, > > ARM64 Linux is supporting both 4KB and 64KB page granularity. Although, Xen > hypercall interface and PV protocol are always based on 4KB page granularity. > > Any attempt to boot a Linux guest with 64KB pages enabled will result to a

Re: [Xen-devel] [PATCH v4 00/20] xen/arm64: Add support for 64KB page in Linux

2015-09-11 Thread Julien Grall
Hi, A quick update on the TODO. On 07/09/15 16:33, Julien Grall wrote: > ARM64 Linux is supporting both 4KB and 64KB page granularity. Although, Xen > hypercall interface and PV protocol are always based on 4KB page granularity. > > Any attempt to boot a Linux guest with 64KB pages enabled will