Messages in this thread | | | Date | Fri, 19 Jan 2001 01:16:29 +0100 | From | Andrea Arcangeli <> | Subject | Re: 2.4.1pre8 slowdown on dbench tests |
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On Thu, Jan 18, 2001 at 03:17:13PM -0200, Marcelo Tosatti wrote: > Jens, can be the -blk patch the reason for the slowdown I'm seeing?
This heuristic is way too aggressive:
/* * Try to keep 128MB max hysteris. If not possible, * use half of RAM */ high_queued_sectors = (total_ram * 2) / 3; low_queued_sectors = high_queued_sectors - MB(128); if (low_queued_sectors < 0) low_queued_sectors = total_ram / 2;
/* * for big RAM machines (>= 384MB), use more for I/O */ if (total_ram >= MB(384)) { high_queued_sectors = (total_ram * 4) / 5; low_queued_sectors = high_queued_sectors - MB(128); }
2/3 of ram locked down in the I/O queue is way too much. 1/3 should be ok. big RAM machines needs way less than 1/3 locked down.
Marcelo can you give a try with `high_queued_sectors = total_ram / 3' and low_queued_sectors = high_queued_sectors / 2 and drop the big ram machine check?
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