On Mon, 27 Apr 2020 17:44:49 +0300
"Yordan Karadzhov (VMware)" <y.karadz@xxxxxxxxx> wrote:
> On 24.04.20 г. 23:12 ч., Steven Rostedt wrote:
> >
> > After applying this patch, I was hitting a lockup with this file:
> >
> > http://rostedt.org/private/trace-all.dat.xz
> >
> > By selecting "Event" and searching for "sched" it would hang at %87
> >
>
> Hi Steven,
> Very well spotted. I am not able to reproduce the bug directly, but I
> guess this is because you are running this on a machine that has 24 CPU
> cores (or 12 and hyper-trading enabled).
Yep (12 and hyperthreading).
>
> > I found the bug below.
> >
> > On Mon, 30 Mar 2020 19:17:22 +0300
> > "Yordan Karadzhov (VMware)" <y.karadz@xxxxxxxxx> wrote:
> >
> >> --- a/kernel-shark/src/KsModels.cpp
> >> +++ b/kernel-shark/src/KsModels.cpp
> >> @@ -52,22 +52,25 @@ size_t KsFilterProxyModel::_search(int column,
> >> const QString &searchText,
> >> search_condition_func cond,
> >> QList<int> *matchList,
> >> + int step,
> >> int first, int last,
> >> QProgressBar *pb,
> >> QLabel *l,
> >> + int *lastRowSearched,
> >> bool notify)
> >> {
> >> int index, row, nRows(last - first + 1);
> >> - int pbCount(1);
> >> + int milestone(1), pbCount(1);
> >> QString item;
> >>
> >> if (nRows > KS_PROGRESS_BAR_MAX)
> >> - pbCount = nRows / (KS_PROGRESS_BAR_MAX - _searchProgress);
> >> + milestone = pbCount = nRows / (KS_PROGRESS_BAR_MAX - step -
> >> + _searchProgress);
>
> The problem will show up if this division has no remainder.
Yeah, I figured.
>
> >> else
> >> _searchProgress = KS_PROGRESS_BAR_MAX - nRows;
> >>
> >> /* Loop over the items of the proxy model. */
> >> - for (index = first; index <= last; ++index) {
> >> + for (index = first; index <= last; index += step) {
> >> /*
> >> * Use the index of the proxy model to retrieve the value
> >> * of the row number in the base model.
> >> @@ -78,17 +81,23 @@ size_t KsFilterProxyModel::_search(int column,
> >> matchList->append(row);
> >>
> >> if (_searchStop) {
> >> - if (notify) {
> >> - _searchProgress = KS_PROGRESS_BAR_MAX;
> >> + if (lastRowSearched)
> >> + *lastRowSearched = index;
> >> +
> >> + if (notify)
> >> _pbCond.notify_one();
> >> - }
> >>
> >> break;
> >> }
> >>
> >> /* Deal with the Progress bar of the seatch. */
> >> - if ((index - first) % pbCount == 0) {
> >> + if ((index - first) > milestone) {
> >
> > Changing the above to:
> >
> > if ((index - first) >= milestone) {
> >
> > fixes it.
>
> Correct.
>
> >
> >> + milestone += pbCount;
> >> if (notify) {
> >> + /*
> >> + * This is a multi-threaded search. Notify
> >> + * the main thread to update the progress bar.
> >> + */
> >> std::lock_guard<std::mutex> lk(_mutex);
> >> ++_searchProgress;
> >> _pbCond.notify_one();
> >> @@ -100,6 +109,7 @@ size_t KsFilterProxyModel::_search(int column,
> >>
> >> if (l)
> >> l->setText(QString(" %1").arg(matchList->count()));
> >> +
> >> QApplication::processEvents();
> >> }
> >> }
> >
> >
> > Otherwise it looks like it leaves out the final update and the
> > code hangs here:
> >
> > /* Start all other threads. */
> > for (int r = 1; r < nThreads; ++r)
> > maps.push_back(std::async(lamSearchMap,
> > startFrom + r,
> > false)); // notify = false
> >
> > while (_searchFSM.getState() == search_state_t::InProgress_s &&
> > _proxyModel.searchProgress() < KS_PROGRESS_BAR_MAX - nThreads) {
>
> Alternative fix can be to changing the above to:
> _proxyModel.searchProgress() < KS_PROGRESS_BAR_MAX - nThreads - 1) {
>
> I would say we can apply both. What do you think?
I'll try it out and let you know.
Thanks Yordan!
-- Steve
>
> Thanks!
> Yordan
>
> > std::unique_lock<std::mutex> lk(_proxyModel._mutex);
> > _proxyModel._pbCond.wait(lk);
> >
> > < It's stuck above >
> >
> > _searchFSM.setProgress(_proxyModel.searchProgress());
> > QApplication::processEvents();
> > }
> >
> >
> > -- Steve
> >
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