| Message ID | 20210304100002.7740-4-osalvador@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Allocate memmap from hotadded memory (per device) | expand |
On 04.03.21 11:00, Oscar Salvador wrote: > Self stored memmap leads to a sparse memory situation which is unsuitable > for workloads that requires large contiguous memory chunks, so make this > an opt-in which needs to be explicitly enabled. > > To control this, let memory_hotplug have its own memory space, as suggested > by David, so we can add memory_hotplug.memmap_on_memory parameter. > > Signed-off-by: Oscar Salvador <osalvador@suse.de> > --- > Documentation/admin-guide/kernel-parameters.txt | 14 ++++++++++++++ > mm/Makefile | 5 ++++- > mm/memory_hotplug.c | 8 +++++++- > 3 files changed, 25 insertions(+), 2 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 04545725f187..e626dab39c60 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -2794,6 +2794,20 @@ > seconds. Use this parameter to check at some > other rate. 0 disables periodic checking. > > + memory_hotplug.memmap_on_memory > + [KNL,X86,ARM] Boolean flag to enable this feature. Right now it can be set on any arch with memory hotplug, right? It's simply not effective. > + Format: {on | off (default)} > + When enabled, memory to build the pages tables for the > + memmap array describing the hot-added range will be taken > + from the range itself, so the memmap page tables will be > + self-hosted. > + Since only single memory device ranges are supported at > + the moment, this option is disabled by default because > + it might have an impact on workloads that needs large > + contiguous memory chunks. > + The state of the flag can be read in > + /sys/module/memory_hotplug/parameters/memmap_on_memory. Maybe want to add that even if enabled, there are cases where it is not effective? > + > memtest= [KNL,X86,ARM,PPC] Enable memtest > Format: <integer> > default : 0 <disable> > diff --git a/mm/Makefile b/mm/Makefile > index 72227b24a616..82ae9482f5e3 100644 > --- a/mm/Makefile > +++ b/mm/Makefile > @@ -58,9 +58,13 @@ obj-y := filemap.o mempool.o oom_kill.o fadvise.o \ > page-alloc-y := page_alloc.o > page-alloc-$(CONFIG_SHUFFLE_PAGE_ALLOCATOR) += shuffle.o > > +# Give 'memory_hotplug' its own module-parameter namespace > +memory-hotplug-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o > + > obj-y += page-alloc.o > obj-y += init-mm.o > obj-y += memblock.o > +obj-y += $(memory-hotplug-y) > > ifdef CONFIG_MMU > obj-$(CONFIG_ADVISE_SYSCALLS) += madvise.o > @@ -83,7 +87,6 @@ obj-$(CONFIG_SLUB) += slub.o > obj-$(CONFIG_KASAN) += kasan/ > obj-$(CONFIG_KFENCE) += kfence/ > obj-$(CONFIG_FAILSLAB) += failslab.o > -obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o > obj-$(CONFIG_MEMTEST) += memtest.o > obj-$(CONFIG_MIGRATION) += migrate.o > obj-$(CONFIG_TRANSPARENT_HUGEPAGE) += huge_memory.o khugepaged.o > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 63e5a0e9a6f3..94b0ec3d2ff2 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -42,7 +42,13 @@ > #include "internal.h" > #include "shuffle.h" > > -static bool memmap_on_memory; > + > +/* > + * memory_hotplug.memmap_on_memory parameter > + */ > +static bool memmap_on_memory __ro_after_init; > +module_param(memmap_on_memory, bool, 0444); > +MODULE_PARM_DESC(memmap_on_memory, "Enable memmap on memory for memory hotplug"); > Wondering if this makes sense getting wrapped in #ifdef CONFIG MHP_MEMMAP_ON_MEMORY just a thought. LGTM Reviewed-by: David Hildenbrand <david@redhat.com>
On Fri, Mar 05, 2021 at 04:35:08PM +0100, David Hildenbrand wrote: > On 04.03.21 11:00, Oscar Salvador wrote: > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > > index 04545725f187..e626dab39c60 100644 > > --- a/Documentation/admin-guide/kernel-parameters.txt > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > @@ -2794,6 +2794,20 @@ > > seconds. Use this parameter to check at some > > other rate. 0 disables periodic checking. > > + memory_hotplug.memmap_on_memory > > + [KNL,X86,ARM] Boolean flag to enable this feature. > > Right now it can be set on any arch with memory hotplug, right? It's simply > not effective. Right. > > + Format: {on | off (default)} > > + When enabled, memory to build the pages tables for the > > + memmap array describing the hot-added range will be taken > > + from the range itself, so the memmap page tables will be > > + self-hosted. > > + Since only single memory device ranges are supported at > > + the moment, this option is disabled by default because > > + it might have an impact on workloads that needs large > > + contiguous memory chunks. > > + The state of the flag can be read in > > + /sys/module/memory_hotplug/parameters/memmap_on_memory. > > Maybe want to add that even if enabled, there are cases where it is not > effective? Sure, I already added a hint. > > +static bool memmap_on_memory __ro_after_init; > > +module_param(memmap_on_memory, bool, 0444); > > +MODULE_PARM_DESC(memmap_on_memory, "Enable memmap on memory for memory hotplug"); > > Wondering if this makes sense getting wrapped in > > #ifdef CONFIG MHP_MEMMAP_ON_MEMORY > > just a thought. Definitely, will wrapp it with MHP_MEMMAP_ON_MEMORY. > > LGTM > > Reviewed-by: David Hildenbrand <david@redhat.com> Thanks!
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 04545725f187..e626dab39c60 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2794,6 +2794,20 @@ seconds. Use this parameter to check at some other rate. 0 disables periodic checking. + memory_hotplug.memmap_on_memory + [KNL,X86,ARM] Boolean flag to enable this feature. + Format: {on | off (default)} + When enabled, memory to build the pages tables for the + memmap array describing the hot-added range will be taken + from the range itself, so the memmap page tables will be + self-hosted. + Since only single memory device ranges are supported at + the moment, this option is disabled by default because + it might have an impact on workloads that needs large + contiguous memory chunks. + The state of the flag can be read in + /sys/module/memory_hotplug/parameters/memmap_on_memory. + memtest= [KNL,X86,ARM,PPC] Enable memtest Format: <integer> default : 0 <disable> diff --git a/mm/Makefile b/mm/Makefile index 72227b24a616..82ae9482f5e3 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -58,9 +58,13 @@ obj-y := filemap.o mempool.o oom_kill.o fadvise.o \ page-alloc-y := page_alloc.o page-alloc-$(CONFIG_SHUFFLE_PAGE_ALLOCATOR) += shuffle.o +# Give 'memory_hotplug' its own module-parameter namespace +memory-hotplug-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o + obj-y += page-alloc.o obj-y += init-mm.o obj-y += memblock.o +obj-y += $(memory-hotplug-y) ifdef CONFIG_MMU obj-$(CONFIG_ADVISE_SYSCALLS) += madvise.o @@ -83,7 +87,6 @@ obj-$(CONFIG_SLUB) += slub.o obj-$(CONFIG_KASAN) += kasan/ obj-$(CONFIG_KFENCE) += kfence/ obj-$(CONFIG_FAILSLAB) += failslab.o -obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o obj-$(CONFIG_MEMTEST) += memtest.o obj-$(CONFIG_MIGRATION) += migrate.o obj-$(CONFIG_TRANSPARENT_HUGEPAGE) += huge_memory.o khugepaged.o diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 63e5a0e9a6f3..94b0ec3d2ff2 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -42,7 +42,13 @@ #include "internal.h" #include "shuffle.h" -static bool memmap_on_memory; + +/* + * memory_hotplug.memmap_on_memory parameter + */ +static bool memmap_on_memory __ro_after_init; +module_param(memmap_on_memory, bool, 0444); +MODULE_PARM_DESC(memmap_on_memory, "Enable memmap on memory for memory hotplug"); /* * online_page_callback contains pointer to current page onlining function.
Self stored memmap leads to a sparse memory situation which is unsuitable for workloads that requires large contiguous memory chunks, so make this an opt-in which needs to be explicitly enabled. To control this, let memory_hotplug have its own memory space, as suggested by David, so we can add memory_hotplug.memmap_on_memory parameter. Signed-off-by: Oscar Salvador <osalvador@suse.de> --- Documentation/admin-guide/kernel-parameters.txt | 14 ++++++++++++++ mm/Makefile | 5 ++++- mm/memory_hotplug.c | 8 +++++++- 3 files changed, 25 insertions(+), 2 deletions(-)