Hi, On Fri, Apr 19, 2019 at 10:08:31PM +0200, Helge Deller wrote: > On 19.04.19 16:28, Mel Gorman wrote: > > On Fri, Apr 19, 2019 at 07:05:21AM -0700, Matthew Wilcox wrote: > >> On Fri, Apr 19, 2019 at 10:43:35AM +0100, Mel Gorman wrote: > >>> DISCONTIG is essentially deprecated and even parisc plans to move to > >>> SPARSEMEM so there is no need to be fancy, this patch simply disables > >>> watermark boosting by default on DISCONTIGMEM. > >> > >> I don't think parisc is the only arch which uses DISCONTIGMEM for !NUMA > >> scenarios. Grepping the arch/ directories shows: > >> > >> alpha (does support NUMA, but also non-NUMA DISCONTIGMEM) > >> arc (for supporting more than 1GB of memory) > >> ia64 (looks complicated ...) > >> m68k (for multiple chunks of memory) > >> mips (does support NUMA but also non-NUMA) > >> parisc (both NUMA and non-NUMA) > >> > >> I'm not sure that these architecture maintainers even know that DISCONTIGMEM > >> is deprecated. Adding linux-arch to the cc. > > > > Poor wording then -- yes, DISCONTIGMEM is still used but look where it's > > used. I find it impossible to believe that any new arch would support > > DISCONTIGMEM or that DISCONTIGMEM would be selected when SPARSEMEM is > > available.`It's even more insane when you consider that SPARSEMEM can be > > extended to support VMEMMAP so that it has similar overhead to FLATMEM > > when mapping pfns to struct pages and vice-versa. > > FYI, on parisc we will switch from DISCONTIGMEM to SPARSEMEM with kernel 5.2. > The patch was quite simple and it's currently in the for-next tree: > https://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux.git/commit/?h=for-next&id=281b718721a5e78288271d632731cea9697749f7 A while ago I've sent a patch that removes ARCH_DISCARD_MEMBLOCK option [1] so the hunk below is not needed: diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig index c8038165b81f..26c215570adf 100644 --- a/arch/parisc/Kconfig +++ b/arch/parisc/Kconfig @@ -36,6 +36,7 @@ config PARISC select GENERIC_STRNCPY_FROM_USER select SYSCTL_ARCH_UNALIGN_ALLOW select SYSCTL_EXCEPTION_TRACE + select ARCH_DISCARD_MEMBLOCK select HAVE_MOD_ARCH_SPECIFIC select VIRT_TO_BUS select MODULES_USE_ELF_RELA [1] https://lore.kernel.org/lkml/1556102150-32517-1-git-send-email-rppt@xxxxxxxxxxxxx/ > Helge > -- Sincerely yours, Mike.
