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Re: [Valgrind-users] 答复: 答复: 答复: 答复: [Help] Valgrind sometime run the program very slowly sometimes , it last at least one hour. can you show me why or some way to analyze it?
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From: Philippe W. <phi...@sk...> - 2018-02-07 20:49:31
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Have you tried with --fair-sched=yes, as suggested in an earlier mail ?
What were/are the results ?
Philippe
On Wed, 2018-02-07 at 07:52 +0000, Wuweijia wrote:
> Hi:
> There are some news about this question. The new code as below, I change from __sync_fetch_and_add to pthread_mutex_xxx
>
> pthread_mutex_lock(&g_mutex);
> int curr = m_nCurrent;
> m_nCurrent += m_nStep;
> pthread_mutex_unlock(&g_mutex);
>
> Now there is no testcases with valgrind running too long, and failed.
>
> But pthread_mutex_lock is not efficient as __sync_fetch_and_add, so the pthread_mutex_lock is just for now, for testing.
>
> And I think there is something related to schedule module of valgrind . why it last too long?
>
> BR
> Owen
>
>
> -----邮件原件-----
> 发件人: John Reiser [mailto:jr...@bi...]
> 发送时间: 2018年1月26日 12:44
> 收件人: val...@li...
> 主题: Re: [Valgrind-users] 答复: 答复: 答复: [Help] Valgrind sometime run the program very slowly sometimes , it last at least one hour. can you show me why or some way to analyze it?
>
> On 01/25/2018 15:37 UTC, Wuweijia wrote:
>
> > Function1:
> > bool CDynamicScheduling::GetProcLoop(
> > int& nBegin,
> > int& nEndPlusOne)
> > {
> > int curr = __sync_fetch_and_add(&m_nCurrent, m_nStep);
>
> How large is 'm_nStep'? [Are you sure?] The overhead expense of switching threads in valgrind would be reduced by making m_nStep as large as possible. It looks like the code in Function2 would produce the same values regardless.
>
>
> > if (curr > m_nEnd)
> > {
> > return false;
> > }
> >
> > nBegin = curr;
> > int limit = m_nEnd + 1;
>
> Local variable 'limit' is unused. By itself this is unimportant, but it might be a clue to something that is not shown here.
>
> > nEndPlusOne = curr + m_nStep;
> > return true;
> > }
> >
> >
> > Function2:
> > ....
> > int beginY, endY;
> > while (pDS->GetProcLoop(beginY, endY)){
> > for (y = beginY; y < endY; y++){
> > for(x = 0; x < dstWDiv2-7; x+=8){
> > vtmp0 = vld2q_u16(&pSrc[(y<<1)*srcStride+(x<<1)]);
> > vtmp1 = vld2q_u16(&pSrc[((y<<1)+1)*srcStride+(x<<1)]);
>
> I hope the actual source contains a comment such as:
> Compute pDst[] as the rounded average of non-overlapping 2x2 blocks of pixels in pSrc[].
>
> > vst1q_u16(&pDst[y*dstStride+x], (vtmp0.val[0] + vtmp0.val[1] + vtmp1.val[0] + vtmp1.val[1] + vdupq_n_u16(2)) >> vdupq_n_u16(2));
> > }
> > for(; x < dstWDiv2; x++){
> > pDst[y*dstStride+x] = (pSrc[(y<<1)*srcStride+(x<<1)] + pSrc[(y<<1)*srcStride+(x<<1)+1] + pSrc[((y<<1)+1)*srcStride+(x<<1)] + pSrc[((y<<1)+1)*srcStride+((x<<1)+1)] + 2) >> 2;
> > }
> > }
> > }
> >
> > return;
> > }
>
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