The request queue was increased from 256 slots to 512 in 2.5.20. The
throughput of `dbench 128' on Randy's 384 megabyte machine fell 40%.
We do need to understand why that happened, and what we can learn from
it. But in the meanwhile I'd suggest that we go back to 256 slots so
that this known problem doesn't impact people's evaluation and tuning
of 2.5 performance.
--- 2.5.22/drivers/block/ll_rw_blk.c~256-requests Sun Jun 16 22:50:18 2002
+++ 2.5.22-akpm/drivers/block/ll_rw_blk.c Sun Jun 16 23:22:46 2002
@@ -2002,8 +2002,8 @@ int __init blk_dev_init(void)
queue_nr_requests = (total_ram >> 8) & ~15; /* One per quarter-megabyte */
if (queue_nr_requests < 32)
queue_nr_requests = 32;
- if (queue_nr_requests > 512)
- queue_nr_requests = 512;
+ if (queue_nr_requests > 256)
+ queue_nr_requests = 256;
/*
* Batch frees according to queue length
-
-
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This archive was generated by hypermail 2b29 : Sun Jun 23 2002 - 22:00:12 EST