Commit 374cac7a authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds

[PATCH] go back to 256 requests per queue

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.
parent 7a1a7f5b
...@@ -2002,8 +2002,8 @@ int __init blk_dev_init(void) ...@@ -2002,8 +2002,8 @@ int __init blk_dev_init(void)
queue_nr_requests = (total_ram >> 8) & ~15; /* One per quarter-megabyte */ queue_nr_requests = (total_ram >> 8) & ~15; /* One per quarter-megabyte */
if (queue_nr_requests < 32) if (queue_nr_requests < 32)
queue_nr_requests = 32; queue_nr_requests = 32;
if (queue_nr_requests > 512) if (queue_nr_requests > 256)
queue_nr_requests = 512; queue_nr_requests = 256;
/* /*
* Batch frees according to queue length * Batch frees according to queue length
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment