Excerpts from Arnd Bergmann's message of Mon Apr 04 17:12:49 +0200 2011:
Ah, right, sorry about that. It needs to be 3072.
Also, better apply this patch to make sure that everything starts at multiples of three.
Without your patch 1.5MB EBS seems like a good bet:
align 805306368 pre 5.42ms on 6.23ms post 2.87ms diff 2.08ms align 402653184 pre 5.41ms on 5.98ms post 2.86ms diff 1.85ms align 201326592 pre 5.58ms on 6.19ms post 2.87ms diff 1.96ms align 100663296 pre 4.6ms on 5.89ms post 2.87ms diff 2.16ms align 50331648 pre 5.08ms on 6.23ms post 2.87ms diff 2.26ms align 25165824 pre 5.32ms on 6.23ms post 2.84ms diff 2.15ms align 12582912 pre 4.3ms on 6.23ms post 2.86ms diff 2.65ms align 6291456 pre 4.77ms on 6.18ms post 2.58ms diff 2.5ms align 3145728 pre 3.9ms on 5.56ms post 2.58ms diff 2.32ms align 1572864 pre 5.36ms on 6.03ms post 2.59ms diff 2.05ms align 786432 pre 3.26ms on 3.47ms post 2.6ms diff 536µs align 393216 pre 3.35ms on 3.42ms post 2.58ms diff 456µs align 196608 pre 3.34ms on 3.43ms post 2.57ms diff 478µs align 98304 pre 3.26ms on 3.42ms post 2.57ms diff 506µs align 49152 pre 3.32ms on 3.45ms post 2.57ms diff 509µs align 24576 pre 3.31ms on 3.4ms post 2.57ms diff 462µs align 12288 pre 3.25ms on 2.9ms post 2.75ms diff -106663 align 6144 pre 2.6ms on 2.55ms post 2.68ms diff -86041n
With your patch applied however the results are a bit odd:
align 603979776 pre 5.46ms on 5.85ms post 2.86ms diff 1.69ms align 402653184 pre 5.54ms on 5.85ms post 2.85ms diff 1.66ms align 301989888 pre 5.09ms on 6.09ms post 2.86ms diff 2.12ms align 201326592 pre 5.48ms on 6.12ms post 2.87ms diff 1.95ms align 150994944 pre 5.46ms on 6.08ms post 2.85ms diff 1.93ms align 100663296 pre 5.19ms on 6.12ms post 2.87ms diff 2.09ms align 75497472 pre 4.56ms on 5.94ms post 2.85ms diff 2.24ms align 50331648 pre 5.69ms on 6.03ms post 2.87ms diff 1.75ms align 37748736 pre 4.69ms on 6.12ms post 2.86ms diff 2.35ms align 25165824 pre 4.94ms on 6.14ms post 2.86ms diff 2.24ms align 18874368 pre 5.45ms on 6.15ms post 2.86ms diff 2ms align 12582912 pre 4.97ms on 6.08ms post 2.85ms diff 2.17ms align 9437184 pre 5.01ms on 5.59ms post 2.85ms diff 1.66ms align 6291456 pre 5.45ms on 6.07ms post 2.67ms diff 2.01ms align 4718592 pre 5.18ms on 5.67ms post 2.67ms diff 1.74ms align 3145728 pre 5.2ms on 5.66ms post 2.67ms diff 1.73ms align 2359296 pre 3.39ms on 3.53ms post 2.67ms diff 500µs align 1572864 pre 5.32ms on 5.95ms post 2.68ms diff 1.95ms align 1179648 pre 3.5ms on 3.53ms post 2.68ms diff 442µs align 786432 pre 3.42ms on 3.57ms post 2.68ms diff 522µs align 589824 pre 3.4ms on 3.56ms post 2.65ms diff 535µs align 393216 pre 3.47ms on 3.57ms post 2.67ms diff 500µs align 294912 pre 3.4ms on 3.54ms post 2.66ms diff 511µs align 196608 pre 3.36ms on 3.55ms post 2.66ms diff 538µs align 147456 pre 3.38ms on 3.6ms post 2.67ms diff 575µs align 98304 pre 3.44ms on 3.57ms post 2.67ms diff 515µs align 73728 pre 3.46ms on 3.51ms post 2.68ms diff 445µs align 49152 pre 3.32ms on 3.55ms post 2.66ms diff 560µs align 36864 pre 3.4ms on 2.98ms post 2.85ms diff -143939 align 24576 pre 3.41ms on 3.51ms post 2.66ms diff 484µs align 18432 pre 3.43ms on 3.49ms post 3.48ms diff 35.3µs align 12288 pre 3.32ms on 2.98ms post 2.85ms diff -105911 align 9216 pre 2.75ms on 2.84ms post 3.14ms diff -104004 align 6144 pre 2.68ms on 2.64ms post 2.75ms diff -69256n
Note the times for 1.5, 2.25 and 3 MB. Around 24k it's also a bit off.
Sascha