On 02/05/2013 08:17 PM, Minchan Kim wrote: > Zsmalloc has two methods 1) copy-based and 2) pte-based to access > allocations that span two pages. You can see history why we supported > two approach from [1]. > > In summary, copy-based method is 3 times fater in x86 while pte-based > is 6 times faster in ARM. > > But it was bad choice that adding hard coding to select architecture > which want to use pte based method. This patch removed it and adds > new Kconfig to select the approach. > > This patch is based on next-20130205. > > [1] https://lkml.org/lkml/2012/7/11/58 > > * Changelog from v1 > * Fix CONFIG_PGTABLE_MAPPING in zsmalloc-main.c - Greg > > Cc: Andrew Morton <[email protected]> > Cc: Seth Jennings <[email protected]> > Cc: Nitin Gupta <[email protected]> > Cc: Dan Magenheimer <[email protected]> > Cc: Konrad Rzeszutek Wilk <[email protected]> > Signed-off-by: Minchan Kim <[email protected]> > --- > drivers/staging/zsmalloc/Kconfig | 12 ++++++++++++ > drivers/staging/zsmalloc/zsmalloc-main.c | 20 +++++--------------- > 2 files changed, 17 insertions(+), 15 deletions(-) > > diff --git a/drivers/staging/zsmalloc/Kconfig > b/drivers/staging/zsmalloc/Kconfig > index 9084565..232b3b6 100644 > --- a/drivers/staging/zsmalloc/Kconfig > +++ b/drivers/staging/zsmalloc/Kconfig > @@ -8,3 +8,15 @@ config ZSMALLOC > non-standard allocator interface where a handle, not a pointer, is > returned by an alloc(). This handle must be mapped in order to > access the allocated space. > + > +config PGTABLE_MAPPING > + bool "Use page table mapping to access allocations that span two > pages" > + depends on ZSMALLOC > + default n > + help > + By default, zsmalloc uses a copy-based object mapping method to access > + allocations that span two pages. However, if a particular architecture > + performs VM mapping faster than copying, then you should select this. > + This causes zsmalloc to use page table mapping rather than copying > + for object mapping. You can check speed with zsmalloc benchmark[1]. > + [1] https://github.com/spartacus06/zsmalloc
Hmm, I'm not sure we want to include this link in the Kconfig. While I don't have any plans to take that repo down, I could see it getting stale at some point for yet-to-be-determined reasons. Of course, without this tool (or something like it) it is hard to know which option is better for your particular platform. Would having this in a Documentation/ file, once one exists, be better? Seth -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
