On 08/21/2013 04:29 PM, Jan Stancek wrote:
>
>
>
> ----- Original Message -----
>> From: "Stanislav Kholmanskikh" <stanislav.kholmansk...@oracle.com>
>> To: ltp-list@lists.sourceforge.net
>> Cc: "vasily isaenko" <vasily.isae...@oracle.com>, jstan...@redhat.com
>> Sent: Wednesday, 21 August, 2013 1:54:58 PM
>> Subject: [PATCH V2 3/3] lib/numa_helper.c: fix nodemask_size
>>
>> Now nodemask_size is rounded up to the next multiple
>> of sizeof(nodemask_t).
> Hi,
>
> Why multiple of nodemask_t? It can be quite large.
Hi.
As nodemask is a pointer to nodemask_t type, so it should point to
memory areas
multiple of sizeof(nodemask_t).
Isn't it?
>
>> Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmansk...@oracle.com>
>> ---
>> testcases/kernel/lib/numa_helper.c | 6 +++---
>> 1 files changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/testcases/kernel/lib/numa_helper.c
>> b/testcases/kernel/lib/numa_helper.c
>> index 4157816..9151583 100644
>> --- a/testcases/kernel/lib/numa_helper.c
>> +++ b/testcases/kernel/lib/numa_helper.c
>> @@ -60,7 +60,7 @@ unsigned long get_max_node(void)
>> #if HAVE_NUMA_H
>> static void get_nodemask_allnodes(nodemask_t * nodemask, unsigned long
>> max_node)
>> {
>> - unsigned long nodemask_size = max_node / 8 + 1;
>> + unsigned long nodemask_size = ALIGN(max_node, sizeof(nodemask_t)*8) / 8;
> Because mask is passed as parameter, we should respect max_node and
> clear only up to byte which holds max_node. So I think we should align
> to next byte only:
>
> unsigned long nodemask_size = ALIGN(max_node, 8) / 8;
I agree but I'm not sure how bytes comprising nodemask_t are handled.
If they are handled in an endianness-dependant way then your approach will
work only on little-endian systems.
So I decided to clear entire region. The same for filter_nodemask_mem.
>
>> int i;
>> char fn[64];
>> struct stat st;
>> @@ -76,7 +76,7 @@ static void get_nodemask_allnodes(nodemask_t * nodemask,
>> unsigned long max_node)
>> static int filter_nodemask_mem(nodemask_t * nodemask, unsigned long
>> max_node)
>> {
>> #if MPOL_F_MEMS_ALLOWED
>> - unsigned long nodemask_size = max_node / 8 + 1;
>> + unsigned long nodemask_size = ALIGN(max_node, sizeof(nodemask_t)*8) / 8;
> Same as above:
> unsigned long nodemask_size = ALIGN(max_node, 8) / 8;
>
>> memset(nodemask, 0, nodemask_size);
>> /*
>> * avoid numa_get_mems_allowed(), because of bug in getpol()
>> @@ -165,7 +165,7 @@ int get_allowed_nodes_arr(int flag, int *num_nodes, int
>> **nodes)
>>
>> #if HAVE_NUMA_H
>> unsigned long max_node = get_max_node();
>> - unsigned long nodemask_size = max_node / 8 + 1;
>> + unsigned long nodemask_size = ALIGN(max_node, sizeof(nodemask_t)*8) / 8;
> This function allocates the nodemask, so we can align to as much as we need.
> I'd expect this to be same as in migrate_pages, align to next long:
>
> unsigned long nodemask_size = ALIGN(max_node / 8, sizeof(long));
This formula may give incorrect results. For example, if max_mode = 66
and sizeof(long) = 8, then
ALIGN(max_node / 8, sizeof(long)) will output 8 and we will lost 2 bits.
The correct output should be 16.
I think as max_node contains number of bits so we should align it on
sizeof(long)*8 boundary and after that divide the final result by 8.
> Regards,
> Jan
>
>>
>> nodemask = malloc(nodemask_size);
>> if (nodes)
>> --
>> 1.7.1
>>
>>
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