search for: 491ms

...marked as MADV_DONTNEED by the hypervisor and shouldn't be given to the host ksmd to scan. Therefore, it is not necessary to zero ballooned pages, which is very time consuming when the page amount is large. The ongoing fast balloon tests show that the time to balloon 7G pages is increased from ~491ms to 2.8 seconds with __GFP_ZERO added. So, this patch removes the flag. Signed-off-by: Wei Wang <wei.w.wang at intel.com> Cc: Michal Hocko <mhocko at kernel.org> Cc: Michael S. Tsirkin <mst at redhat.com> --- mm/balloon_compaction.c | 2 +- 1 file changed, 1 insertion(+), 1 delet...

...marked as MADV_DONTNEED by the hypervisor and shouldn't be given to the host ksmd to scan. Therefore, it is not necessary to zero ballooned pages, which is very time consuming when the page amount is large. The ongoing fast balloon tests show that the time to balloon 7G pages is increased from ~491ms to 2.8 seconds with __GFP_ZERO added. So, this patch removes the flag. Signed-off-by: Wei Wang <wei.w.wang at intel.com> Cc: Michal Hocko <mhocko at kernel.org> Cc: Michael S. Tsirkin <mst at redhat.com> --- mm/balloon_compaction.c | 2 +- 1 file changed, 1 insertion(+), 1 delet...

...marked as MADV_DONTNEED by the hypervisor and shouldn't be given to the host ksmd to scan. Therefore, it is not necessary to zero ballooned pages, which is very time consuming when the page amount is large. The ongoing fast balloon tests show that the time to balloon 7G pages is increased from ~491ms to 2.8 seconds with __GFP_ZERO added. So, this patch removes the flag. Signed-off-by: Wei Wang <wei.w.wang at intel.com> --- mm/balloon_compaction.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c index 9075aa5..b06d9fe 1...

...marked as MADV_DONTNEED by the hypervisor and shouldn't be given to the host ksmd to scan. Therefore, it is not necessary to zero ballooned pages, which is very time consuming when the page amount is large. The ongoing fast balloon tests show that the time to balloon 7G pages is increased from ~491ms to 2.8 seconds with __GFP_ZERO added. So, this patch removes the flag. Signed-off-by: Wei Wang <wei.w.wang at intel.com> --- mm/balloon_compaction.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c index 9075aa5..b06d9fe 1...

...d to scan. I find MADV_DONTNEED reference still quite confusing. What do you think about the following wording instead: " Zeroying ballon pages is rather time consuming, especially when a lot of pages are in flight. E.g. 7GB worth of ballooned memory takes 2.8s with __GFP_ZERO while it takes ~491ms without it. The original commit argued that zeroying will help ksmd to merge these pages on the host but this argument is assuming that the host actually marks balloon pages for ksm which is not universally true. So we pay performance penalty for something that even might not be used in the end whi...

...ges to the host in > sgs. An sg describes a chunk of guest physically continuous pages. > With this mechanism, step 4) can also be optimized by doing address > translation and madvise() in chunks rather than page by page. > > With this new feature, the above ballooning process takes ~491ms > resulting in an improvement of ~88%. > I found a recent mm patch, bb01b64cfab7c22f3848cb73dc0c2b46b8d38499 , zeros all the ballooned pages, which is very time consuming. Tests show that the time to balloon 7G pages is increased from ~491 ms to 2.8 seconds with the above patch. How about...

...ges to the host in > sgs. An sg describes a chunk of guest physically continuous pages. > With this mechanism, step 4) can also be optimized by doing address > translation and madvise() in chunks rather than page by page. > > With this new feature, the above ballooning process takes ~491ms > resulting in an improvement of ~88%. > I found a recent mm patch, bb01b64cfab7c22f3848cb73dc0c2b46b8d38499 , zeros all the ballooned pages, which is very time consuming. Tests show that the time to balloon 7G pages is increased from ~491 ms to 2.8 seconds with the above patch. How about...

...md to scan. Could you point me where this MADV_DONTNEED is done, please? > Therefore, it is not > necessary to zero ballooned pages, which is very time consuming when > the page amount is large. The ongoing fast balloon tests show that the > time to balloon 7G pages is increased from ~491ms to 2.8 seconds with > __GFP_ZERO added. So, this patch removes the flag. Please make it obvious that this is a revert of bb01b64cfab7 ("mm/balloon_compaction.c: enqueue zero page to balloon device"). > Signed-off-by: Wei Wang <wei.w.wang at intel.com> > --- > mm/ballo...

...EED by the hypervisor and > shouldn't be given to the host ksmd to scan. Therefore, it is not > necessary to zero ballooned pages, which is very time consuming when > the page amount is large. The ongoing fast balloon tests show that the > time to balloon 7G pages is increased from ~491ms to 2.8 seconds with > __GFP_ZERO added. So, this patch removes the flag. > > Signed-off-by: Wei Wang <wei.w.wang at intel.com> > Cc: Michal Hocko <mhocko at kernel.org> > Cc: Michael S. Tsirkin <mst at redhat.com> > --- > mm/balloon_compaction.c | 2 +- >...

...r and > > shouldn't be given to the host ksmd to scan. Therefore, it is not > > necessary to zero ballooned pages, which is very time consuming when > > the page amount is large. The ongoing fast balloon tests show that the > > time to balloon 7G pages is increased from ~491ms to 2.8 seconds with > > __GFP_ZERO added. So, this patch removes the flag. > > > > Signed-off-by: Wei Wang <wei.w.wang at intel.com> > > Cc: Michal Hocko <mhocko at kernel.org> > > Cc: Michael S. Tsirkin <mst at redhat.com> > > --- > > m...

...r and > > shouldn't be given to the host ksmd to scan. Therefore, it is not > > necessary to zero ballooned pages, which is very time consuming when > > the page amount is large. The ongoing fast balloon tests show that the > > time to balloon 7G pages is increased from ~491ms to 2.8 seconds with > > __GFP_ZERO added. So, this patch removes the flag. > > > > Signed-off-by: Wei Wang <wei.w.wang at intel.com> > > Cc: Michal Hocko <mhocko at kernel.org> > > Cc: Michael S. Tsirkin <mst at redhat.com> > > --- > > m...

...om/qemu/qemu/blob/master/hw/virtio/virtio-balloon.c > >> Therefore, it is not >> necessary to zero ballooned pages, which is very time consuming when >> the page amount is large. The ongoing fast balloon tests show that the >> time to balloon 7G pages is increased from ~491ms to 2.8 seconds with >> __GFP_ZERO added. So, this patch removes the flag. > Please make it obvious that this is a revert of bb01b64cfab7 > ("mm/balloon_compaction.c: enqueue zero page to balloon device"). > > Ok, will do. Best, Wei

...om/qemu/qemu/blob/master/hw/virtio/virtio-balloon.c > >> Therefore, it is not >> necessary to zero ballooned pages, which is very time consuming when >> the page amount is large. The ongoing fast balloon tests show that the >> time to balloon 7G pages is increased from ~491ms to 2.8 seconds with >> __GFP_ZERO added. So, this patch removes the flag. > Please make it obvious that this is a revert of bb01b64cfab7 > ("mm/balloon_compaction.c: enqueue zero page to balloon device"). > > Ok, will do. Best, Wei

...ep 2) by transferring pages to the host in sgs. An sg describes a chunk of guest physically continuous pages. With this mechanism, step 4) can also be optimized by doing address translation and madvise() in chunks rather than page by page. With this new feature, the above ballooning process takes ~491ms resulting in an improvement of ~88%. TODO: optimize stage 1) by allocating/freeing a chunk of pages instead of a single page each time. Signed-off-by: Wei Wang <wei.w.wang at intel.com> Signed-off-by: Liang Li <liang.z.li at intel.com> Suggested-by: Michael S. Tsirkin <mst at redha...

This patch series enhances the existing virtio-balloon with the following new features: 1) fast ballooning: transfer ballooned pages between the guest and host in chunks using sgs, instead of one by one; and 2) cmdq: a new virtqueue to send commands between the device and driver. Currently, it supports commands to report memory stats (replace the old statq mechanism) and report guest unused pages.

This patch series enhances the existing virtio-balloon with the following new features: 1) fast ballooning: transfer ballooned pages between the guest and host in chunks using sgs, instead of one by one; and 2) cmdq: a new virtqueue to send commands between the device and driver. Currently, it supports commands to report memory stats (replace the old statq mechanism) and report guest unused pages.