[Flashbench] Results for Sandisk class 4 "SDHC card"

[Arnd Bergmann]

On Monday 04 April 2011, Sascha Silbe wrote:
> 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

Ok, that is pretty clear.

> 
> 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.

I should have made clearer that with the patch applied, you no longer need to
pass an odd blocksize, but again use 1024 byte blocks with the -a test, though
not the --open-au test. The test above tries both power-of-two multiples of
the block size and three times those values.

	Arnd