lkml.org 
[lkml]   [2013]   [Jan]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCHv2 4/9] staging: zsmalloc: make CLASS_DELTA relative to PAGE_SIZE
On 01/24/2013 06:17 PM, Nitin Gupta wrote:
> On Mon, Jan 7, 2013 at 12:24 PM, Seth Jennings
> <sjenning@linux.vnet.ibm.com> wrote:
>> Right now ZS_SIZE_CLASS_DELTA is hardcoded to be 16. This
>> creates 254 classes for systems with 4k pages. However, on
>> PPC64 with 64k pages, it creates 4095 classes which is far
>> too many.
>>
>> This patch makes ZS_SIZE_CLASS_DELTA relative to PAGE_SIZE
>> so that regardless of the page size, there will be the same
>> number of classes.
>>
>> Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
>> ---
>> drivers/staging/zsmalloc/zsmalloc-main.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/drivers/staging/zsmalloc/zsmalloc-main.c
>> index 825e124..3543047 100644
>> --- a/drivers/staging/zsmalloc/zsmalloc-main.c
>> +++ b/drivers/staging/zsmalloc/zsmalloc-main.c
>> @@ -141,7 +141,7 @@
>> * ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN
>> * (reason above)
>> */
>> -#define ZS_SIZE_CLASS_DELTA 16
>> +#define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> 8)
>> #define ZS_SIZE_CLASSES ((ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) / \
>> ZS_SIZE_CLASS_DELTA + 1)
>>
>
> Actually, there is no point creating size classes beyond [M/(M+1)] * PAGE_SIZE
> where M is the maximum number of system pages in a zspage.

Agreed.

> All size classes
> beyond this size can be collapsed with PAGE_SIZE size class. This can
> significantly reduce number of size classes created but I think changes needed
> to do this would be more involved, so perhaps, should be done in another
> patch.

I agree there could be some optimization here, but those extra classes
really aren't doing any harm that I can see.

> Can you please resend part of this series (patch 1 to patch 4) which deals
> just with zsmalloc separately? I haven't yet looked into zswap itself so would
> help with zsmalloc bits are separated out.

Working it now.

Thanks,
Seth



\
 
 \ /
  Last update: 2013-01-25 18:21    [W:0.212 / U:2.352 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site