Do you have tested it with a real workload and big memory ? (100-200GB for example).
I'm curious to see what happen with a lot of alloc/desalloc and fragmentation. ----- Mail original ----- De: "Andreas Steinel" <a.stei...@gmail.com> À: "aderumier" <aderum...@odiso.com> Cc: "Daniel Hunsaker" <danhunsa...@gmail.com>, "dietmar" <diet...@proxmox.com>, "pve-devel" <pve-devel@pve.proxmox.com> Envoyé: Mercredi 9 Septembre 2015 18:41:37 Objet: Re: [pve-devel] disabling transparent hugepage by default like kernel 2.6.32 ? I tried with a simple 128 MB Jessie Box and 'mbw' program and got these results: mbw -n 100 50 | grep AVG > hthp_1_gthp_1 HostTransparentHugePages_(1|0)_GuestTransparentHugePages_(1|0) Test hthp_0_gthp_0 AVG Method: MEMCPY Elapsed: 0.01728 MiB: 50.00000 Copy: 2893.123 MiB/s AVG Method: DUMB Elapsed: 0.01770 MiB: 50.00000 Copy: 2824.581 MiB/s AVG Method: MCBLOCK Elapsed: 0.01111 MiB: 50.00000 Copy: 4499.575 MiB/s Test hthp_0_gthp_1 AVG Method: MEMCPY Elapsed: 0.01927 MiB: 50.00000 Copy: 2594.132 MiB/s AVG Method: DUMB Elapsed: 0.01869 MiB: 50.00000 Copy: 2674.970 MiB/s AVG Method: MCBLOCK Elapsed: 0.01157 MiB: 50.00000 Copy: 4322.956 MiB/s Test hthp_1_gthp_0 AVG Method: MEMCPY Elapsed: 0.01645 MiB: 50.00000 Copy: 3039.115 MiB/s AVG Method: DUMB Elapsed: 0.01572 MiB: 50.00000 Copy: 3180.148 MiB/s AVG Method: MCBLOCK Elapsed: 0.00987 MiB: 50.00000 Copy: 5066.072 MiB/s Test hthp_1_gthp_1 AVG Method: MEMCPY Elapsed: 0.02151 MiB: 50.00000 Copy: 2324.526 MiB/s AVG Method: DUMB Elapsed: 0.01553 MiB: 50.00000 Copy: 3220.203 MiB/s AVG Method: MCBLOCK Elapsed: 0.00998 MiB: 50.00000 Copy: 5009.729 MiB/s On Wed, Sep 9, 2015 at 5:43 PM, Alexandre DERUMIER <aderum...@odiso.com> wrote: >>>In my benchmarks, THP increase the memory transaction speed by 5-10% in the >>>KVM guest if THP is activated on the host side, not in the VM side. I know >>>that THP for databases is bad, but we are not using THP in the guest >>where >>>the database lives. Can someone provide some benchmarks for that case or >>>further information? Any suggestions? > > Oh, good to known. > > How much memory do you use it your vm ? what is the database software ? > > ----- Mail original ----- > De: "Andreas Steinel" <a.stei...@gmail.com> > À: "Daniel Hunsaker" <danhunsa...@gmail.com> > Cc: "aderumier" <aderum...@odiso.com>, "dietmar" <diet...@proxmox.com>, > "pve-devel" <pve-devel@pve.proxmox.com> > Envoyé: Mercredi 9 Septembre 2015 16:32:23 > Objet: Re: [pve-devel] disabling transparent hugepage by default like kernel > 2.6.32 ? > > Hi, > In my benchmarks, THP increase the memory transaction speed by 5-10% in the > KVM guest if THP is activated on the host side, not in the VM side. I know > that THP for databases is bad, but we are not using THP in the guest where > the database lives. Can someone provide some benchmarks for that case or > further information? Any suggestions? > > On Wed, Sep 9, 2015 at 3:45 PM, Daniel Hunsaker < danhunsa...@gmail.com > > wrote: > > > > > What about setting CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS = N? As I understand > it, "not set" means "use the default setting the kernel devs think is the > most sane for normal use", which in this case would be Y... > > On Wed, Sep 9, 2015, 06:58 Alexandre DERUMIER < aderum...@odiso.com > wrote: > > >>>I could set it in kernel config, for example: >>> >>>CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y >>> >>>would that help? > > Well, this is like "echo madvise > > /sys/kernel/mm/transparent_hugepage/enabled" > > But I don't see how to set never. > > maybe > > # CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS is not set > # CONFIG_TRANSPARENT_HUGEPAGE_MADVISE is not set > > > But I don't known how to unset CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS in the new > pve-kernel package makefile ? > > > I have tried to add > > PVE_CONFIG_OPTS= \ > .. > -d CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS \ > .. > > but it don't seem to work, I still have CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS=Y > in .config > > Any idea ? > > > > ----- Mail original ----- > De: "dietmar" < diet...@proxmox.com > > À: "aderumier" < aderum...@odiso.com >, "pve-devel" < > pve-devel@pve.proxmox.com > > Envoyé: Mercredi 9 Septembre 2015 06:33:05 > Objet: Re: [pve-devel] disabling transparent hugepage by default like kernel > 2.6.32 ? > >> I think it's better to disable it by default. >> >> echo never > /sys/kernel/mm/transparent_hugepage/enabled. >> >> (I don't known what is the best way to disable it by default) > > I could set it in kernel config, for example: > > CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y > > would that help? > _______________________________________________ > pve-devel mailing list > pve-devel@pve.proxmox.com > http://pve.proxmox.com/cgi-bin/mailman/listinfo/pve-devel > > > > > _______________________________________________ > pve-devel mailing list > pve-devel@pve.proxmox.com > http://pve.proxmox.com/cgi-bin/mailman/listinfo/pve-devel > > > > _______________________________________________ pve-devel mailing list pve-devel@pve.proxmox.com http://pve.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
