Yingyi Bu has uploaded a new change for review.
https://asterix-gerrit.ics.uci.edu/341
Change subject: Performance fix for BufferCache. The dpid of a page of file is
calculated by fileid<<32 + pageid. But BufferCache.hash(long dpid) returns the
hash value dpid%pageMap.length. In many cases, the asterix configuration
results in power-of-2 pageMap.length (b
......................................................................
Performance fix for BufferCache.
The dpid of a page of file is calculated by fileid<<32 + pageid.
But BufferCache.hash(long dpid) returns the hash value dpid%pageMap.length.
In many cases, the asterix configuration results in power-of-2 pageMap.length
(buffer-cache-size/page-size), which makes fileid useless.
That used to result in serious consequences: different partitions contend for
the same cache bucket (which contains a link list of size #partitions) for most
of the time and therefore the CPU couldn't be saturated.
Change-Id: I4afc406d612e569e23f65afdedc469459235ce7d
---
M
hyracks/hyracks-storage-common/src/main/java/edu/uci/ics/hyracks/storage/common/buffercache/BufferCache.java
1 file changed, 2 insertions(+), 1 deletion(-)
git pull ssh://asterix-gerrit.ics.uci.edu:29418/hyracks refs/changes/41/341/1
diff --git
a/hyracks/hyracks-storage-common/src/main/java/edu/uci/ics/hyracks/storage/common/buffercache/BufferCache.java
b/hyracks/hyracks-storage-common/src/main/java/edu/uci/ics/hyracks/storage/common/buffercache/BufferCache.java
index 94ad801..9a18610 100644
---
a/hyracks/hyracks-storage-common/src/main/java/edu/uci/ics/hyracks/storage/common/buffercache/BufferCache.java
+++
b/hyracks/hyracks-storage-common/src/main/java/edu/uci/ics/hyracks/storage/common/buffercache/BufferCache.java
@@ -441,7 +441,8 @@
}
private int hash(long dpid) {
- return (int) (dpid % pageMap.length);
+ int hashValue = (int) (dpid ^ (dpid >>> 32));
+ return hashValue % pageMap.length;
}
private static class CacheBucket {
--
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I4afc406d612e569e23f65afdedc469459235ce7d
Gerrit-PatchSet: 1
Gerrit-Project: hyracks
Gerrit-Branch: master
Gerrit-Owner: Yingyi Bu <[email protected]>
