| Message ID | 1340643332-5653-4-git-send-email-lcapitulino@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 06/25/2012 11:55 AM, Luiz Capitulino wrote: > Allow to enable/disable memory merging during run-time. > > This is implemented by extending the qemu_set_mem_merge() function. > > To test on HMP: > > (qemu) set_memory_merge on > (qemu) set_memory_merge off > > Signed-off-by: Luiz Capitulino<lcapitulino@redhat.com> Is there a requirement to tweak KSM dynamically on a per-VM basis or was this just a nice to have? I can certainly understand wanting to run your VMs without KSM but not wanting to have to muck with global configuration values. I would suspect that people would either overcommit or not overcommit as a global decision. Once you overcommit even one machine, you potentially put your whole system in danger of swap. Regards, Anthony Liguori > --- > exec.c | 15 +++++++++++++++ > hmp-commands.hx | 14 ++++++++++++++ > hmp.c | 6 ++++++ > hmp.h | 1 + > monitor.c | 6 ++++++ > osdep.h | 2 ++ > qapi-schema.json | 18 ++++++++++++++++++ > qmp-commands.hx | 5 +++++ > 8 files changed, 67 insertions(+) > > diff --git a/exec.c b/exec.c > index e29b27f..1fa82b4 100644 > --- a/exec.c > +++ b/exec.c > @@ -2504,6 +2504,21 @@ void qemu_ram_set_idstr(ram_addr_t addr, const char *name, DeviceState *dev) > > void qemu_set_mem_merge(bool value) > { > + const RAMBlock *block; > + > + if (ram_list.merge_memory == value) { > + /* do nothing */ > + return; > + } > + > + /* XXX: report errors? */ > + QLIST_FOREACH(block,&ram_list.blocks, next) { > + if (block->flags& RAM_MERGEABLE) { > + qemu_madvise(block->host, block->length, > + value ? QEMU_MADV_MERGEABLE : QEMU_MADV_UNMERGEABLE); > + } > + } > + > ram_list.merge_memory = value; > } > > diff --git a/hmp-commands.hx b/hmp-commands.hx > index f5d9d91..6ab3852 100644 > --- a/hmp-commands.hx > +++ b/hmp-commands.hx > @@ -366,6 +366,20 @@ Wakeup guest from suspend. > ETEXI > > { > + .name = "set_memory_merge", > + .args_type = "status:b", > + .params = "status", > + .help = "enable/disable memory merge support", > + .mhandler.cmd = hmp_set_memory_merge, > + }, > + > +STEXI > +@item set_memory_merge > +@findex set_memory_merge > +Enable/disable memory merge support > +ETEXI > + > + { > .name = "gdbserver", > .args_type = "device:s?", > .params = "[device]", > diff --git a/hmp.c b/hmp.c > index b9cec1d..063cb3e 100644 > --- a/hmp.c > +++ b/hmp.c > @@ -1000,3 +1000,9 @@ void hmp_netdev_del(Monitor *mon, const QDict *qdict) > qmp_netdev_del(id,&err); > hmp_handle_error(mon,&err); > } > + > +void hmp_set_memory_merge(Monitor *mon, const QDict *qdict) > +{ > + bool enable = qdict_get_bool(qdict, "status"); > + qmp_set_memory_merge(enable, NULL); > +} > diff --git a/hmp.h b/hmp.h > index 79d138d..d884733 100644 > --- a/hmp.h > +++ b/hmp.h > @@ -64,5 +64,6 @@ void hmp_device_del(Monitor *mon, const QDict *qdict); > void hmp_dump_guest_memory(Monitor *mon, const QDict *qdict); > void hmp_netdev_add(Monitor *mon, const QDict *qdict); > void hmp_netdev_del(Monitor *mon, const QDict *qdict); > +void hmp_set_memory_merge(Monitor *mon, const QDict *qdict); > > #endif > diff --git a/monitor.c b/monitor.c > index f6107ba..c7f9015 100644 > --- a/monitor.c > +++ b/monitor.c > @@ -4813,3 +4813,9 @@ int monitor_read_block_device_key(Monitor *mon, const char *device, > > return monitor_read_bdrv_key_start(mon, bs, completion_cb, opaque); > } > + > +/* FIXME: move to qmp.c, although including memory.h doesn't work there */ > +void qmp_set_memory_merge(bool enable, Error **errp) > +{ > + memory_global_set_merge(enable); > +} > diff --git a/osdep.h b/osdep.h > index 3ea4af0..f5563c2 100644 > --- a/osdep.h > +++ b/osdep.h > @@ -97,8 +97,10 @@ void qemu_vfree(void *ptr); > #endif > #ifdef MADV_MERGEABLE > #define QEMU_MADV_MERGEABLE MADV_MERGEABLE > +#define QEMU_MADV_UNMERGEABLE MADV_UNMERGEABLE > #else > #define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID > +#define QEMU_MADV_UNMERGEABLE QEMU_MADV_INVALID > #endif > > #elif defined(CONFIG_POSIX_MADVISE) > diff --git a/qapi-schema.json b/qapi-schema.json > index 3b6e346..0b99bc0 100644 > --- a/qapi-schema.json > +++ b/qapi-schema.json > @@ -1862,3 +1862,21 @@ > # Since: 0.14.0 > ## > { 'command': 'netdev_del', 'data': {'id': 'str'} } > + > +## > +# @set-memory-merge: > +# > +# Enable or disable memory merge support. On Linux systems, this enables > +# or disables KSM support. > +# > +# @enable: true (enables memory merging) or false (disables memory merging) > +# > +# Returns: Nothing on success > +# > +# Note: this command never fails. The only possible reason for a failure > +# is when the host doesn't support memory merging, but that's not reported > +# by this command, it will just return success. > +# > +# Since: 1.2.0 > +## > +{ 'command': 'set-memory-merge', 'data': { 'enable': 'bool' } } > diff --git a/qmp-commands.hx b/qmp-commands.hx > index 2e1a38e..74530b9 100644 > --- a/qmp-commands.hx > +++ b/qmp-commands.hx > @@ -2209,3 +2209,8 @@ EQMP > .args_type = "implements:s?,abstract:b?", > .mhandler.cmd_new = qmp_marshal_input_qom_list_types, > }, > + { > + .name = "set-memory-merge", > + .args_type = "enable:b", > + .mhandler.cmd_new = qmp_marshal_input_set_memory_merge, > + },
On Mon, Jun 25, 2012 at 05:05:45PM -0500, Anthony Liguori wrote: > On 06/25/2012 11:55 AM, Luiz Capitulino wrote: > >Allow to enable/disable memory merging during run-time. > > > >This is implemented by extending the qemu_set_mem_merge() function. > > > >To test on HMP: > > > > (qemu) set_memory_merge on > > (qemu) set_memory_merge off > > > >Signed-off-by: Luiz Capitulino<lcapitulino@redhat.com> > > Is there a requirement to tweak KSM dynamically on a per-VM basis or > was this just a nice to have? > > I can certainly understand wanting to run your VMs without KSM but > not wanting to have to muck with global configuration values. > > I would suspect that people would either overcommit or not > overcommit as a global decision. Once you overcommit even one > machine, you potentially put your whole system in danger of swap. I tend to agree, this monitor commands feels like a feature without a clear usecase. Daniel
On Tue, 26 Jun 2012 10:25:22 +0100 "Daniel P. Berrange" <berrange@redhat.com> wrote: > On Mon, Jun 25, 2012 at 05:05:45PM -0500, Anthony Liguori wrote: > > On 06/25/2012 11:55 AM, Luiz Capitulino wrote: > > >Allow to enable/disable memory merging during run-time. > > > > > >This is implemented by extending the qemu_set_mem_merge() function. > > > > > >To test on HMP: > > > > > > (qemu) set_memory_merge on > > > (qemu) set_memory_merge off > > > > > >Signed-off-by: Luiz Capitulino<lcapitulino@redhat.com> > > > > Is there a requirement to tweak KSM dynamically on a per-VM basis or > > was this just a nice to have? > > > > I can certainly understand wanting to run your VMs without KSM but > > not wanting to have to muck with global configuration values. > > > > I would suspect that people would either overcommit or not > > overcommit as a global decision. Once you overcommit even one > > machine, you potentially put your whole system in danger of swap. > > I tend to agree, this monitor commands feels like a feature without a > clear usecase. Well, the request for it came from libvirt and I implemented it without wondering much about it. But if you think it's not worth it, I'll just drop it.
On Tue, Jun 26, 2012 at 09:53:32AM -0300, Luiz Capitulino wrote: > On Tue, 26 Jun 2012 10:25:22 +0100 > "Daniel P. Berrange" <berrange@redhat.com> wrote: > > > On Mon, Jun 25, 2012 at 05:05:45PM -0500, Anthony Liguori wrote: > > > On 06/25/2012 11:55 AM, Luiz Capitulino wrote: > > > >Allow to enable/disable memory merging during run-time. > > > > > > > >This is implemented by extending the qemu_set_mem_merge() function. > > > > > > > >To test on HMP: > > > > > > > > (qemu) set_memory_merge on > > > > (qemu) set_memory_merge off > > > > > > > >Signed-off-by: Luiz Capitulino<lcapitulino@redhat.com> > > > > > > Is there a requirement to tweak KSM dynamically on a per-VM basis or > > > was this just a nice to have? > > > > > > I can certainly understand wanting to run your VMs without KSM but > > > not wanting to have to muck with global configuration values. > > > > > > I would suspect that people would either overcommit or not > > > overcommit as a global decision. Once you overcommit even one > > > machine, you potentially put your whole system in danger of swap. > > > > I tend to agree, this monitor commands feels like a feature without a > > clear usecase. > > Well, the request for it came from libvirt and I implemented it without > wondering much about it. Hmm, I think that must have been a mis-understanding soemwhere, because I'm not aware of having asked for a monitor command! All we desire for libvirt is for the custom command line argument hack that was done in RHEL KVM trees, to be turned into a upstream accepted command line arg. > But if you think it's not worth it, I'll just drop it. Sounds good :-) Daniel
diff --git a/exec.c b/exec.c index e29b27f..1fa82b4 100644 --- a/exec.c +++ b/exec.c @@ -2504,6 +2504,21 @@ void qemu_ram_set_idstr(ram_addr_t addr, const char *name, DeviceState *dev) void qemu_set_mem_merge(bool value) { + const RAMBlock *block; + + if (ram_list.merge_memory == value) { + /* do nothing */ + return; + } + + /* XXX: report errors? */ + QLIST_FOREACH(block, &ram_list.blocks, next) { + if (block->flags & RAM_MERGEABLE) { + qemu_madvise(block->host, block->length, + value ? QEMU_MADV_MERGEABLE : QEMU_MADV_UNMERGEABLE); + } + } + ram_list.merge_memory = value; } diff --git a/hmp-commands.hx b/hmp-commands.hx index f5d9d91..6ab3852 100644 --- a/hmp-commands.hx +++ b/hmp-commands.hx @@ -366,6 +366,20 @@ Wakeup guest from suspend. ETEXI { + .name = "set_memory_merge", + .args_type = "status:b", + .params = "status", + .help = "enable/disable memory merge support", + .mhandler.cmd = hmp_set_memory_merge, + }, + +STEXI +@item set_memory_merge +@findex set_memory_merge +Enable/disable memory merge support +ETEXI + + { .name = "gdbserver", .args_type = "device:s?", .params = "[device]", diff --git a/hmp.c b/hmp.c index b9cec1d..063cb3e 100644 --- a/hmp.c +++ b/hmp.c @@ -1000,3 +1000,9 @@ void hmp_netdev_del(Monitor *mon, const QDict *qdict) qmp_netdev_del(id, &err); hmp_handle_error(mon, &err); } + +void hmp_set_memory_merge(Monitor *mon, const QDict *qdict) +{ + bool enable = qdict_get_bool(qdict, "status"); + qmp_set_memory_merge(enable, NULL); +} diff --git a/hmp.h b/hmp.h index 79d138d..d884733 100644 --- a/hmp.h +++ b/hmp.h @@ -64,5 +64,6 @@ void hmp_device_del(Monitor *mon, const QDict *qdict); void hmp_dump_guest_memory(Monitor *mon, const QDict *qdict); void hmp_netdev_add(Monitor *mon, const QDict *qdict); void hmp_netdev_del(Monitor *mon, const QDict *qdict); +void hmp_set_memory_merge(Monitor *mon, const QDict *qdict); #endif diff --git a/monitor.c b/monitor.c index f6107ba..c7f9015 100644 --- a/monitor.c +++ b/monitor.c @@ -4813,3 +4813,9 @@ int monitor_read_block_device_key(Monitor *mon, const char *device, return monitor_read_bdrv_key_start(mon, bs, completion_cb, opaque); } + +/* FIXME: move to qmp.c, although including memory.h doesn't work there */ +void qmp_set_memory_merge(bool enable, Error **errp) +{ + memory_global_set_merge(enable); +} diff --git a/osdep.h b/osdep.h index 3ea4af0..f5563c2 100644 --- a/osdep.h +++ b/osdep.h @@ -97,8 +97,10 @@ void qemu_vfree(void *ptr); #endif #ifdef MADV_MERGEABLE #define QEMU_MADV_MERGEABLE MADV_MERGEABLE +#define QEMU_MADV_UNMERGEABLE MADV_UNMERGEABLE #else #define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID +#define QEMU_MADV_UNMERGEABLE QEMU_MADV_INVALID #endif #elif defined(CONFIG_POSIX_MADVISE) diff --git a/qapi-schema.json b/qapi-schema.json index 3b6e346..0b99bc0 100644 --- a/qapi-schema.json +++ b/qapi-schema.json @@ -1862,3 +1862,21 @@ # Since: 0.14.0 ## { 'command': 'netdev_del', 'data': {'id': 'str'} } + +## +# @set-memory-merge: +# +# Enable or disable memory merge support. On Linux systems, this enables +# or disables KSM support. +# +# @enable: true (enables memory merging) or false (disables memory merging) +# +# Returns: Nothing on success +# +# Note: this command never fails. The only possible reason for a failure +# is when the host doesn't support memory merging, but that's not reported +# by this command, it will just return success. +# +# Since: 1.2.0 +## +{ 'command': 'set-memory-merge', 'data': { 'enable': 'bool' } } diff --git a/qmp-commands.hx b/qmp-commands.hx index 2e1a38e..74530b9 100644 --- a/qmp-commands.hx +++ b/qmp-commands.hx @@ -2209,3 +2209,8 @@ EQMP .args_type = "implements:s?,abstract:b?", .mhandler.cmd_new = qmp_marshal_input_qom_list_types, }, + { + .name = "set-memory-merge", + .args_type = "enable:b", + .mhandler.cmd_new = qmp_marshal_input_set_memory_merge, + },
Allow to enable/disable memory merging during run-time. This is implemented by extending the qemu_set_mem_merge() function. To test on HMP: (qemu) set_memory_merge on (qemu) set_memory_merge off Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> --- exec.c | 15 +++++++++++++++ hmp-commands.hx | 14 ++++++++++++++ hmp.c | 6 ++++++ hmp.h | 1 + monitor.c | 6 ++++++ osdep.h | 2 ++ qapi-schema.json | 18 ++++++++++++++++++ qmp-commands.hx | 5 +++++ 8 files changed, 67 insertions(+)