Messages in this thread | | | Date | Tue, 30 Jun 2015 10:45:54 +0800 | From | Xishi Qiu <> | Subject | Re: [RFC v2 PATCH 2/8] mm: introduce MIGRATE_MIRROR to manage the mirrored pages |
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On 2015/6/29 15:32, Kamezawa Hiroyuki wrote:
> On 2015/06/27 11:24, Xishi Qiu wrote: >> This patch introduces a new migratetype called "MIGRATE_MIRROR", it is used to >> allocate mirrored pages. >> When cat /proc/pagetypeinfo, you can see the count of free mirrored blocks. >> >> Signed-off-by: Xishi Qiu <qiuxishi@huawei.com> > > My fear about this approarch is that this may break something existing. > > Now, when we add MIGRATE_MIRROR type, we'll hide attributes of pageblocks as > MIGRATE_UNMOVABOLE, MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE. > > Logically, MIRROR attribute is independent from page mobility and this overwrites > will make some information lost. > > Then, > >> --- >> include/linux/mmzone.h | 9 +++++++++ >> mm/page_alloc.c | 3 +++ >> mm/vmstat.c | 3 +++ >> 3 files changed, 15 insertions(+) >> >> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h >> index 54d74f6..54e891a 100644 >> --- a/include/linux/mmzone.h >> +++ b/include/linux/mmzone.h >> @@ -39,6 +39,9 @@ enum { >> MIGRATE_UNMOVABLE, >> MIGRATE_RECLAIMABLE, >> MIGRATE_MOVABLE, >> +#ifdef CONFIG_MEMORY_MIRROR >> + MIGRATE_MIRROR, >> +#endif > > I think > MIGRATE_MIRROR_UNMOVABLE, > MIGRATE_MIRROR_RECLAIMABLE, > MIGRATE_MIRROR_MOVABLE, <== adding this may need discuss. > MIGRATE_MIRROR_RESERVED, <== reserved pages should be maintained per mirrored/unmirrored. >
Hi Kame,
You mean add 3 or 4 new migratetype?
> should be added with the following fallback list. > > /* > * MIRROR page range is defined by firmware at boot. The range is limited > * and is used only for kernel memory mirroring. > */ > [MIGRATE_UNMOVABLE_MIRROR] = {MIGRATE_RECLAIMABLE_MIRROR, MIGRATE_RESERVE} > [MIGRATE_RECLAIMABLE_MIRROR] = {MIGRATE_UNMOVABLE_MIRROR, MIGRATE_RESERVE} >
Why not like this: {MIGRATE_RECLAIMABLE_MIRROR, MIGRATE_MIRROR_RESERVED, MIGRATE_RESERVE}
> Then, we'll not lose the original information of "Reclaiable Pages". > > One problem here is whteher we should have MIGRATE_RESERVE_MIRROR. > > If we never allow users to allocate mirrored memory, we should have MIGRATE_RESERVE_MIRROR. > But it seems to require much more code change to do that. > > Creating a zone or adding an attribues to zones are another design choice. >
If we add a new zone, mirror_zone will span others, I'm worry about this maybe have problems.
Thanks, Xishi Qiu
> Anyway, your patch doesn't takes care of reserved memory calculation at this point. > Please check setup_zone_migrate_reserve() That will be a problem. > > Thanks, > -Kame >
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