4 Commits (5f4a5e79ea4481111273c11bdf11256f74ea539e)

Author	SHA1	Message	Date
Ganesh Vernekar	50ae4e298b	Fix magic number in docs (#7998) ... Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>	4 years ago
Simon Pasquier	d634785944	tsdb/docs: fix head chunks directory + link from README (#7309) ... Signed-off-by: Simon Pasquier <spasquie@redhat.com>	5 years ago
Ganesh Vernekar	d4b9fe801f	M-map full chunks of Head from disk (#6679) ... When appending to the head and a chunk is full it is flushed to the disk and m-mapped (memory mapped) to free up memory Prom startup now happens in these stages - Iterate the m-maped chunks from disk and keep a map of series reference to its slice of mmapped chunks. - Iterate the WAL as usual. Whenever we create a new series, look for it's mmapped chunks in the map created before and add it to that series. If a head chunk is corrupted the currpted one and all chunks after that are deleted and the data after the corruption is recovered from the existing WAL which means that a corruption in m-mapped files results in NO data loss. [Mmaped chunks format](https://github.com/prometheus/prometheus/blob/master/tsdb/docs/format/head_chunks.md) - main difference is that the chunk for mmaping now also includes series reference because there is no index for mapping series to chunks. [The block chunks](https://github.com/prometheus/prometheus/blob/master/tsdb/docs/format/chunks.md) are accessed from the index which includes the offsets for the chunks in the chunks file - example - chunks of series ID have offsets 200, 500 etc in the chunk files. In case of mmaped chunks, the offsets are stored in memory and accessed from that. During WAL replay, these offsets are restored by iterating all m-mapped chunks as stated above by matching the series id present in the chunk header and offset of that chunk in that file. **Prombench results** _WAL Replay_ 1h Wal reply time 30% less wal reply time - 4m31 vs 3m36 2h Wal reply time 20% less wal reply time - 8m16 vs 7m _Memory During WAL Replay_ High Churn: 10-15% less RAM - 32gb vs 28gb 20% less RAM after compaction 34gb vs 27gb No Churn: 20-30% less RAM - 23gb vs 18gb 40% less RAM after compaction 32.5gb vs 20gb Screenshots are in [this comment](https://github.com/prometheus/prometheus/pull/6679#issuecomment-621678932) Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>	5 years ago
Ganesh Vernekar	e50fdbc70c	Live m-mapping of chunks on disk (#6830) ... * Live m-mapping of chunks on disk Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in> * Fix review comments Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in> * Fix review comments Part 2 Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in> * Fix review comments Part 3 Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in> * Fix review comments Part 4 Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in> * Attempt to fix windows bug Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>	5 years ago