| Message ID | 1556188531-20728-1-git-send-email-rppt@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/Kconfig: update "Memory Model" help text | expand |
On Thu 25-04-19 13:35:31, Mike Rapoport wrote: > The help describing the memory model selection is outdated. It still says > that SPARSEMEM is experimental and DISCONTIGMEM is a preferred over > SPARSEMEM. > > Update the help text for the relevant options: > * add a generic help for the "Memory Model" prompt > * add description for FLATMEM > * reduce the description of DISCONTIGMEM and add a deprecation note > * prefer SPARSEMEM over DISCONTIGMEM > > Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Michal Hocko <mhocko@suse.com> > --- > mm/Kconfig | 48 +++++++++++++++++++++++------------------------- > 1 file changed, 23 insertions(+), 25 deletions(-) > > diff --git a/mm/Kconfig b/mm/Kconfig > index 25c71eb8a7db..8f7ae4d71b77 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -11,23 +11,24 @@ choice > default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT > default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT > default FLATMEM_MANUAL > + help > + This option allows you to change some of the ways that > + Linux manages its memory internally. Most users will > + only have one option here selected by the architecture > + configuration. This is normal. > > config FLATMEM_MANUAL > bool "Flat Memory" > depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE > help > - This option allows you to change some of the ways that > - Linux manages its memory internally. Most users will > - only have one option here: FLATMEM. This is normal > - and a correct option. > - > - Some users of more advanced features like NUMA and > - memory hotplug may have different options here. > - DISCONTIGMEM is a more mature, better tested system, > - but is incompatible with memory hotplug and may suffer > - decreased performance over SPARSEMEM. If unsure between > - "Sparse Memory" and "Discontiguous Memory", choose > - "Discontiguous Memory". > + This option is best suited for non-NUMA systems with > + flat address space. The FLATMEM is the most efficient > + system in terms of performance and resource consumption > + and it is the best option for smaller systems. > + > + For systems that have holes in their physical address > + spaces and for features like NUMA and memory hotplug, > + choose "Sparse Memory" > > If unsure, choose this option (Flat Memory) over any other. > > @@ -38,29 +39,26 @@ config DISCONTIGMEM_MANUAL > This option provides enhanced support for discontiguous > memory systems, over FLATMEM. These systems have holes > in their physical address spaces, and this option provides > - more efficient handling of these holes. However, the vast > - majority of hardware has quite flat address spaces, and > - can have degraded performance from the extra overhead that > - this option imposes. > + more efficient handling of these holes. > > - Many NUMA configurations will have this as the only option. > + Although "Discontiguous Memory" is still used by several > + architectures, it is considered deprecated in favor of > + "Sparse Memory". > > - If unsure, choose "Flat Memory" over this option. > + If unsure, choose "Sparse Memory" over this option. > > config SPARSEMEM_MANUAL > bool "Sparse Memory" > depends on ARCH_SPARSEMEM_ENABLE > help > This will be the only option for some systems, including > - memory hotplug systems. This is normal. > + memory hot-plug systems. This is normal. > > - For many other systems, this will be an alternative to > - "Discontiguous Memory". This option provides some potential > - performance benefits, along with decreased code complexity, > - but it is newer, and more experimental. > + This option provides efficient support for systems with > + holes is their physical address space and allows memory > + hot-plug and hot-remove. > > - If unsure, choose "Discontiguous Memory" or "Flat Memory" > - over this option. > + If unsure, choose "Flat Memory" over this option. > > endchoice > > -- > 2.7.4
diff --git a/mm/Kconfig b/mm/Kconfig index 25c71eb8a7db..8f7ae4d71b77 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -11,23 +11,24 @@ choice default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT default FLATMEM_MANUAL + help + This option allows you to change some of the ways that + Linux manages its memory internally. Most users will + only have one option here selected by the architecture + configuration. This is normal. config FLATMEM_MANUAL bool "Flat Memory" depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE help - This option allows you to change some of the ways that - Linux manages its memory internally. Most users will - only have one option here: FLATMEM. This is normal - and a correct option. - - Some users of more advanced features like NUMA and - memory hotplug may have different options here. - DISCONTIGMEM is a more mature, better tested system, - but is incompatible with memory hotplug and may suffer - decreased performance over SPARSEMEM. If unsure between - "Sparse Memory" and "Discontiguous Memory", choose - "Discontiguous Memory". + This option is best suited for non-NUMA systems with + flat address space. The FLATMEM is the most efficient + system in terms of performance and resource consumption + and it is the best option for smaller systems. + + For systems that have holes in their physical address + spaces and for features like NUMA and memory hotplug, + choose "Sparse Memory" If unsure, choose this option (Flat Memory) over any other. @@ -38,29 +39,26 @@ config DISCONTIGMEM_MANUAL This option provides enhanced support for discontiguous memory systems, over FLATMEM. These systems have holes in their physical address spaces, and this option provides - more efficient handling of these holes. However, the vast - majority of hardware has quite flat address spaces, and - can have degraded performance from the extra overhead that - this option imposes. + more efficient handling of these holes. - Many NUMA configurations will have this as the only option. + Although "Discontiguous Memory" is still used by several + architectures, it is considered deprecated in favor of + "Sparse Memory". - If unsure, choose "Flat Memory" over this option. + If unsure, choose "Sparse Memory" over this option. config SPARSEMEM_MANUAL bool "Sparse Memory" depends on ARCH_SPARSEMEM_ENABLE help This will be the only option for some systems, including - memory hotplug systems. This is normal. + memory hot-plug systems. This is normal. - For many other systems, this will be an alternative to - "Discontiguous Memory". This option provides some potential - performance benefits, along with decreased code complexity, - but it is newer, and more experimental. + This option provides efficient support for systems with + holes is their physical address space and allows memory + hot-plug and hot-remove. - If unsure, choose "Discontiguous Memory" or "Flat Memory" - over this option. + If unsure, choose "Flat Memory" over this option. endchoice
The help describing the memory model selection is outdated. It still says that SPARSEMEM is experimental and DISCONTIGMEM is a preferred over SPARSEMEM. Update the help text for the relevant options: * add a generic help for the "Memory Model" prompt * add description for FLATMEM * reduce the description of DISCONTIGMEM and add a deprecation note * prefer SPARSEMEM over DISCONTIGMEM Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> --- mm/Kconfig | 48 +++++++++++++++++++++++------------------------- 1 file changed, 23 insertions(+), 25 deletions(-)