I'm doing performance test for HDFS. I'm using HDFS C++ API. I notice that most of the reads take up to 5 microseconds. But some of reads take 500-800 microseconds. What could be the reason, considering all the data is in OS cache? No disk access should be occur.
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What do you mean all the data is in OS cache? – OneCricketeer Jan 25 '18 at 21:35
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I've added CachePool, and added all the data to it. It's stored in off-heap, which is managed by OS. I can see from /proc/meminfo that it's in OS cache. – user1289 Jan 26 '18 at 06:58