similar to: dramatic performance slowdown due to THP allocation failure with full pagecache

Thanks for the reply Daniel, However I think you slightly misunderstood the scenario... On 14 November 2017 at 10:32, Daniel P. Berrange <berrange@redhat.com> wrote: > IOW, if your application has a certain expectation of performance that can only > be satisfied by having the KVM guest backed by huge pages, then you should > really change to explicitly reserve huge pages for the

On 14 November 2017 at 10:56, Daniel P. Berrange <berrange@redhat.com> wrote: > Oh well THP usage inside the guest is then not really anything todo with > virt, just a regular Linux questions, so not sure libvirt is the best > place to ask. True, I just hoped you or one of the other devs might have some insight on reclaim behaviour that would provide a clue. I guess I'll try a

On Tue, Nov 14, 2017 at 10:23:56AM -0700, Blair Bethwaite wrote: > Hi all, > > This is not really a libvirt issue but I'm hoping some of the smart folks > here will know more about this problem... > > We have noticed when running some HPC applications on our OpenStack > (libvirt+KVM) cloud that the same application occasionally performs much > worse (4-5x slowdown)

On Tue, Nov 14, 2017 at 10:52:03AM -0700, Blair Bethwaite wrote: > Thanks for the reply Daniel, > > However I think you slightly misunderstood the scenario... > > On 14 November 2017 at 10:32, Daniel P. Berrange <berrange@redhat.com> wrote: > > IOW, if your application has a certain expectation of performance that can only > > be satisfied by having the KVM guest

This series renames pmd_mknotpresent() as pmd_mknotvalid(). Before that it drops an existing pmd_mknotpresent() definition from powerpc platform which was never required as it defines it's pmdp_invalidate() through subscribing __HAVE_ARCH_PMDP_INVALIDATE. This does not create any functional change. This rename was suggested by Catalin during a previous discussion while we were trying to

A migrating transparent huge page has to already be unmapped. Otherwise, the page could be modified while it is being copied to a new page and data could be lost. The function __split_huge_pmd() checks for a PMD migration entry before calling __split_huge_pmd_locked() leading one to think that __split_huge_pmd_locked() can handle splitting a migrating PMD. However, the code always increments the

This series renames pmd_mknotpresent() as pmd_mkinvalid(). Before that it drops an existing pmd_mknotpresent() definition from powerpc platform which was never required as it defines it's pmdp_invalidate() through subscribing __HAVE_ARCH_PMDP_INVALIDATE. This does not create any functional change. This rename was suggested by Catalin during a previous discussion while we were trying to change

On 19 Jun 2020, at 17:56, Ralph Campbell wrote: > Transparent huge page allocation policy is controlled by several sysfs > variables. Rather than expose these to each device driver that needs to > allocate THPs, provide a helper function. > > Signed-off-by: Ralph Campbell <rcampbell at nvidia.com> > --- > include/linux/gfp.h | 10 ++++++++++ > mm/huge_memory.c |

On 12.03.20 08:49, Hui Zhu wrote: > If the guest kernel has many fragmentation pages, use virtio_balloon > will split THP of QEMU when it calls MADV_DONTNEED madvise to release > the balloon pages. > This is an example in a VM with 1G memory 1CPU: > cat /proc/meminfo | grep AnonHugePages: > AnonHugePages: 0 kB > > usemem --punch-holes -s -1 800m & > >

On 12.03.20 08:49, Hui Zhu wrote: > If the guest kernel has many fragmentation pages, use virtio_balloon > will split THP of QEMU when it calls MADV_DONTNEED madvise to release > the balloon pages. > This is an example in a VM with 1G memory 1CPU: > cat /proc/meminfo | grep AnonHugePages: > AnonHugePages: 0 kB > > usemem --punch-holes -s -1 800m & > >

Dear R users/developers, simple comparison of code execution time of R 2.7.1 and R 2.7.2 shows a dramatic slowdown of the newer version. Rprof() identifies .Call function as a main cause (see the code below). What happened with R 2.7.2? Kind regards Marek Wielgosz Bayes Consulting ######### Probably useful info ############### ### CPU: Core2Duo T 7300, 2 GB RAM ### WIN XP ### both standard

pmd_present() is expected to test positive after pmdp_mknotpresent() as the PMD entry still points to a valid huge page in memory. pmdp_mknotpresent() implies that given PMD entry is just invalidated from MMU perspective while still holding on to pmd_page() referred valid huge page thus also clearing pmd_present() test. This creates the following situation which is counter intuitive.

A couple of months ago I reported some problems with a batch of Tyan K8SSA (S3870) based machines. We are continuing to have an odd problem with these boxes, and if anyone has seen something similar elsewhere, I'd appreciate hearing about it. These boxes are running Centos 4.4 x86_64 with kernel 2.6.9-42.0.3.ELsmp. They are dual Opteron 265's (dual core) with 4x2GB DIMM's. The

On Mon, Mar 11, 2019 at 03:40:31PM +0800, Jason Wang wrote: > > On 2019/3/9 ??3:48, Andrea Arcangeli wrote: > > Hello Jeson, > > > > On Fri, Mar 08, 2019 at 04:50:36PM +0800, Jason Wang wrote: > > > Just to make sure I understand here. For boosting through huge TLB, do > > > you mean we can do that in the future (e.g by mapping more userspace > >

On Mon, Mar 11, 2019 at 03:40:31PM +0800, Jason Wang wrote: > > On 2019/3/9 ??3:48, Andrea Arcangeli wrote: > > Hello Jeson, > > > > On Fri, Mar 08, 2019 at 04:50:36PM +0800, Jason Wang wrote: > > > Just to make sure I understand here. For boosting through huge TLB, do > > > you mean we can do that in the future (e.g by mapping more userspace > >

Hi all, In IRC last night Dan helpfully confirmed my analysis of an issue we are seeing attempting to launch high memory KVM guests backed by hugepages... In this case the guests have 240GB of memory allocated from two host NUMA nodes to two guest NUMA nodes. The trouble is that allocating the hugepage backed qemu process seems to take longer than the 30s QEMU_JOB_WAIT_TIME and so libvirt then

Hi, I was wondering about the ARC and its interaction with the VM pagecache... When a file on a ZFS filesystem is mmaped, does the ARC cache get mapped to the process'' virtual memory? Or is there another copy? -Manoj

On Mon, Jun 22, 2020 at 4:02 PM John Hubbard <jhubbard at nvidia.com> wrote: > > On 2020-06-22 15:33, Yang Shi wrote: > > On Mon, Jun 22, 2020 at 3:30 PM Yang Shi <shy828301 at gmail.com> wrote: > >> On Mon, Jun 22, 2020 at 2:53 PM Zi Yan <ziy at nvidia.com> wrote: > >>> On 22 Jun 2020, at 17:31, Ralph Campbell wrote: > >>>> On

On Mon, Jun 22, 2020 at 3:30 PM Yang Shi <shy828301 at gmail.com> wrote: > > On Mon, Jun 22, 2020 at 2:53 PM Zi Yan <ziy at nvidia.com> wrote: > > > > On 22 Jun 2020, at 17:31, Ralph Campbell wrote: > > > > > On 6/22/20 1:10 PM, Zi Yan wrote: > > >> On 22 Jun 2020, at 15:36, Ralph Campbell wrote: > > >> > > >>> On

On Tue, Dec 25, 2018 at 06:05:25PM +0800, Jason Wang wrote: > > On 2018/12/25 ??2:10, Michael S. Tsirkin wrote: > > On Mon, Dec 24, 2018 at 03:53:16PM +0800, Jason Wang wrote: > > > On 2018/12/14 ??8:36, Michael S. Tsirkin wrote: > > > > On Fri, Dec 14, 2018 at 11:57:35AM +0800, Jason Wang wrote: > > > > > On 2018/12/13 ??11:44, Michael S. Tsirkin