Hello mysql,
I've resenty tried to becnhmark mysql in really simple case.
I need to select indexes really fast so I did "select * from pages
where hash=11" there was a key on hash and the query returned only
one row. The query was constant and server ad no other load.
I've run this on 2CPU PIII-700 under 2.2.18aa2 and on one CPU
PIII700 on 2.4.2 The results are about 3300 req/sec and the second
one about 1800 req/sec. Unix domain sockets was used.
I found the rather huge number of context swithches in first case:
2 0 0 3296 265244 104848 111472 0 0 0 0 103 27570 41 19 40
2 0 0 3296 265244 104848 111472 0 0 0 0 103 27690 38 21 41
0 0 0 3296 265344 104848 111472 0 0 0 0 104 26405 37 18 46
the second one looked better, but not much if you'll look at about 2
times speed difference:
1 0 0 24 58656 1480 298180 0 0 0 0 105 7946 84 16 0
1 0 0 24 58656 1480 298180 0 0 0 0 106 7942 88 12 0
2 0 0 24 58656 1480 298180 0 0 0 4 110 7968 82 18 0
1 0 0 24 58656 1480 298180 0 0 0 0 105 7966 81 19 0
1 0 0 24 58656 1480 298180 0 0 0 0 105 7965 81 19 0
1 0 0 24 58656 1480 298180 0 0 0 0 105 7948 83 17 0
1 0 0 24 58656 1480 298180 0 0 0 0 105 7964 85 15 0
I tried to run dumb query "select 10" and got about 7000 queries on
second machine - which is 4 times faster then query which touches the
table.
Has anyone any ideas about if this speed is peek - I have heard
people having 10000 of inserts/sec into table with no indexes with
mysql and so on so I was a bit surprised about this low perfomance,
which is more likely to be not because of connection or pharsing
speed as "select 10" works fast, and just the I/O needed should not
take so much then everything should be in memory.
The another story is - I've tried few time ago read speed of reiserfs
- I created 1000000 of files, each ten bytes in size and I was able
to read this file set in speed of 25000/sec - I mean open/read/close
- so select speed of about 2K queries per second looks quite
surprising, then most of this time is not because of communication
but because of really accessing the table.
--
Best regards,
Peter mailto:[EMAIL PROTECTED]
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