art with code


Intel X25-V SSD

Bought an Intel X25-V 40GB SSD to do some random read benchmarking. Don't stick it into a PATA controller driven SATA port, as that limits the bandwidth to 70 MB/s and random access times to 5 ms.

Sequential read speed on the unused disk was limited by the SATA bus. So I guess it's not actually reading anything for unused blocks, just generating a string of zeroes on the controller and sending it back. Would be pretty amusing to have a special disk driver that keeps a list of the unused blocks in system RAM and generates the data on the CPU for any read accesses to them. You could probably keep it all in L1 and get nice bogus 4k random read benchmark numbers. "1 ns access latency!?? 100 GB/s random read bandwidth??? Whaaaat?" (An allocation bitfield for 80 gigs in 512k blocks is about 20 kB. Increase blocksize or add RLE for bigger volumes.)

Read speed on actual data was around 200 MB/s. Average random read time for a 4k block was 0.038 ms with 128 threads and 0.31 ms with a single thread. So the controller can do 8 reads in parallel. Which is nice for a cheapo SSD.

Didn't really test write performance apart than doing a cursory check. And yes, it is low bandwidth. 40 MB/s streaming writes. So it's best used as a random read drive.

Might make a nice random read array with 6 drives or somesuch. Hypothetically: 48 parallel reads, 160 000 4k reads per second (650 MB/s). And then all you need is software that can take advantage of that.

Getting flash chip latencies lower would be good.
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Built art installations, web sites, graphics libraries, web browsers, mobile apps, desktop apps, media player themes, many nutty prototypes