From b47a5499a0d2591c09e93d1edb3c8827f6353c49 Mon Sep 17 00:00:00 2001 From: Zhiqiang Wang Date: Tue, 7 Apr 2015 14:23:38 +0800 Subject: [PATCH] librbd: don't do readahead when m_readahead_pos reaching limit When m_readahead_pos reaches the limit, there's no need to call _compute_readahead to calculate the readahead. Just return with no readahead. Signed-off-by: Zhiqiang Wang --- src/common/Readahead.cc | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/src/common/Readahead.cc b/src/common/Readahead.cc index 77ab92eba4ff..b1ee2e099c6f 100644 --- a/src/common/Readahead.cc +++ b/src/common/Readahead.cc @@ -30,6 +30,10 @@ Readahead::extent_t Readahead::update(const vector& extents, uint64_t for (vector::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 extent = _compute_readahead(limit); m_lock.Unlock(); return extent; @@ -38,6 +42,10 @@ Readahead::extent_t Readahead::update(const vector& 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; } -- 2.47.3