On 05/17/2012 09:56 AM, Guan Xuetao wrote:

On Thu, 2012-05-17 at 09:07 +0900, Minchan Kim wrote:

quoted

On 05/16/2012 04:28 PM, Guan Xuetao wrote:

quoted

On Wed, 2012-05-16 at 11:05 +0900, Minchan Kim wrote:

quoted

zsmalloc uses set_pte and __flush_tlb_one for performance but
many architecture don't support it. so this patch removes
set_pte and __flush_tlb_one which are x86 dependency.
Instead of it, use local_flush_tlb_kernel_range which are available
by more architectures. It would be better than supporting only x86
and last patch in series will enable again with supporting
local_flush_tlb_kernel_range in x86.

About local_flush_tlb_kernel_range,
If architecture is very smart, it could flush only tlb entries related to vaddr.
If architecture is smart, it could flush only tlb entries related to a CPU.
If architecture is _NOT_ smart, it could flush all entries of all CPUs.
So, it would be best to support both portability and performance.

Cc: Russell King <redacted>
Cc: Ralf Baechle <redacted>
Cc: Paul Mundt <redacted>
Cc: Guan Xuetao <redacted>
Cc: Chen Liqin <redacted>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---

Need double check about supporting local_flush_tlb_kernel_range
in ARM, MIPS, SUPERH maintainers. And I will Ccing unicore32 and
score maintainers because arch directory in those arch have
local_flush_tlb_kernel_range, too but I'm very unfamiliar with those
architecture so pass it to maintainers.
I didn't coded up dumb local_flush_tlb_kernel_range which flush
all cpus. I expect someone need ZSMALLOC will implement it easily in future.
Seth might support it in PowerPC. :)


 drivers/staging/zsmalloc/Kconfig         |    6 ++---
 drivers/staging/zsmalloc/zsmalloc-main.c |   36 +++++++++++++++++++++---------
 drivers/staging/zsmalloc/zsmalloc_int.h  |    1 -
 3 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/drivers/staging/zsmalloc/Kconfig b/drivers/staging/zsmalloc/Kconfig
index a5ab720..def2483 100644
--- a/drivers/staging/zsmalloc/Kconfig
+++ b/drivers/staging/zsmalloc/Kconfig

@@ -1,9 +1,9 @@
 config ZSMALLOC
 	tristate "Memory allocator for compressed pages"
-	# X86 dependency is because of the use of __flush_tlb_one and set_pte
+	# arch dependency is because of the use of local_unmap_kernel_range
 	# in zsmalloc-main.c.
-	# TODO: convert these to portable functions
-	depends on X86
+	# TODO: implement local_unmap_kernel_range in all architecture.
+	depends on (ARM || MIPS || SUPERH)

I suggest removing above line, so if I want to use zsmalloc, I could
enable this configuration easily.

I don't get it. What do you mean?
If I remove above line, compile error will happen if arch doesn't support local_unmap_kernel_range.

If I want to use zsmalloc, I will verify local_unmap_kernel_range
function. In fact, only local_flush_tlb_kernel_range need to be
considered. So, just keeping the default option 'n' is enough.

I don't think so.
It's terrible experience if all users have to look up local_flush_tlb_kernel_range of arch for using zsmalloc.

BTW, does unicore32 support that function?
If so, I would like to add unicore32 in Kconfig.

-- 
Kind regards,
Minchan Kim

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