On Wed, Feb 06, 2013 at 10:47:16AM -0600, Seth Jennings wrote: > 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 <akpm@xxxxxxxxxxxxxxxxxxxx> > > Cc: Seth Jennings <sjenning@xxxxxxxxxxxxxxxxxx> > > Cc: Nitin Gupta <ngupta@xxxxxxxxxx> > > Cc: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> > > Cc: Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx> > > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> > > --- > > 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? It could be better. Then, Let's point out that documentataion in Kconfig. Okay, Let's sort it out. > > Seth > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>