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Merge pull request #4281 from wonzhq/readahead

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librbd: readahead fixes

Reviewed-by: Josh Durgin <jdurgin@redhat.com>
This commit is contained in:
Josh Durgin 2015-04-07 14:47:44 -07:00
commit 25015f9aeb
1 changed files with 12 additions and 0 deletions
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12
src/common/Readahead.cc
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@ -30,6 +30,10 @@ Readahead::extent_t Readahead::update(const vector<extent_t>& extents, uint64_t
for (vector<extent_t>::const_iterator p = extents.begin(); p != extents.end(); ++p) {
_observe_read(p->first, p->second);
}
if (m_readahead_pos >= limit) {
m_lock.Unlock();
return extent_t(0, 0);
}
pair<uint64_t, uint64_t> extent = _compute_readahead(limit);
m_lock.Unlock();
return extent;
@ -38,6 +42,10 @@ Readahead::extent_t Readahead::update(const vector<extent_t>& extents, uint64_t
Readahead::extent_t Readahead::update(uint64_t offset, uint64_t length, uint64_t limit) {
m_lock.Lock();
_observe_read(offset, length);
if (m_readahead_pos >= limit) {
m_lock.Unlock();
return extent_t(0, 0);
}
extent_t extent = _compute_readahead(limit);
m_lock.Unlock();
return extent;
@ -52,6 +60,7 @@ void Readahead::_observe_read(uint64_t offset, uint64_t length) {
m_consec_read_bytes = 0;
m_readahead_trigger_pos = 0;
m_readahead_size = 0;
m_readahead_pos = 0;
}
m_last_pos = offset + length;
}
@ -70,6 +79,9 @@ Readahead::extent_t Readahead::_compute_readahead(uint64_t limit) {
} else {
// continuing readahead trigger
m_readahead_size *= 2;
if (m_last_pos > m_readahead_pos) {
m_readahead_pos = m_last_pos;
}
}
m_readahead_size = MAX(m_readahead_size, m_readahead_min_bytes);
m_readahead_size = MIN(m_readahead_size, m_readahead_max_bytes);