[PATCH v4] Improve the performance of --num-threads -d 31

[Atsushi Kumagai]

Hello,

This is just a quick note to inform you.
I measured the memory consumption with -d31 by VmHWM in
/proc/PID/status and compared them between v3 and v4 since
Minfei said the problem only occurs in v4.

            |          VmHWM[kB]
num-thread  |      v3            v4
------------+--------------------------
     1      |    20,516        20,516
     2      |    20,624        20,628
     4      |    20,832        20,832
     8      |    21,292        21,288
    16      |    22,240        22,236
    32      |    24,096        24,100
    64      |    27,900        27,888

According to this result, the problem we face seems not just
any lack of memory issue.

BTW, the memory consumption increases depending on num-thread,
I think it should be considered in the calculate_cyclic_buffer_size().


Thanks,
Atsushi Kumagai

diff --git a/makedumpfile.c b/makedumpfile.c
index 4075f3e..d5626f9 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -44,6 +44,14 @@ extern int find_vmemmap();

 char filename_stdout[] = FILENAME_STDOUT;

+void
+print_VmHWM(void)
+{
+       char command[64];
+       sprintf(command, "grep VmHWM /proc/%d/status", getpid());
+       system(command);
+}
+
 /* Cache statistics */
 static unsigned long long      cache_hit;
 static unsigned long long      cache_miss;
@@ -11185,5 +11193,7 @@ out:
        }
        free_elf_info();

+       print_VmHWM();
+
        return retcd;
 }


>Hi, Zhou.
>
>I'm on holiday now, you can ask other people to help test, if necessary.
>
>Thanks
>Minfei
>
>> 在 2016年3月24日，12:29，Zhou, Wenjian/周文剑 <zhouwj-fnst at cn.fujitsu.com> 写道：
>>
>> Hello Minfei,
>>
>> How do these two patches work?
>>
>> --
>> Thanks
>> Zhou
>>
>>> On 03/18/2016 01:48 PM, "Zhou, Wenjian/周文剑" wrote:
>>>> On 03/18/2016 12:16 PM, Minfei Huang wrote:
>>>>> On 03/18/16 at 10:46am, "Zhou, Wenjian/周文剑" wrote:
>>>>> Hello Minfei,
>>>>>
>>>>> Since I can't produce the bug, I reviewed the patch and wrote an increment patch.
>>>>> Though there are some bugs in the increment patch,
>>>>> I wonder if the previous bug still exists with this patch.
>>>>> Could you help me confirm it?
>>>>
>>>> Ok. I will help verify this increasing patch.
>>>
>>> Thank you very much.
>>>
>>>>>
>>>>> And I have another question.
>>>>> Did it only occur in patch v4?
>>>>
>>>> This issue doesn't exist in v3. I have pasted the test result with
>>>> --num-thread 32 in that thread.
>>>>
>>>> applied makedumpfile with option -d 31 --num-threads 32
>>>> real    3m3.533s
>>>
>>> Oh, then the patch in the previous mail may not work.
>>>
>>> I'm appreciated if you can also test the patch in this letter.
>>>
>>> I introduced semaphore to fix the bug in the v3.
>>> So I want to know if it is this which affects the result.
>>> The attached patch is based on v4, used to remove semaohore.
>>>
>>>
>>>
>>> _______________________________________________
>>> kexec mailing list
>>> kexec at lists.infradead.org
>>> http://lists.infradead.org/mailman/listinfo/kexec
>>
>>
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