4 ms·
RAID checksums computation looks like an obvious possibility. We'd need a battery backup for the VRAM, too :)
by wazoox 16y ago
RAID checksums computation looks like an obvious possibility. We'd need a battery backup for the VRAM, too :)
- rbanffy 16y agoI think this is very memory intensive. Remember the GPU would have to calculate block checksums preferably from the main memory where the buffer resides. Maybe block deduplication could be done this way. If the block is a dupe, skipping its allocation on the disk (it would save at least one block write) could offset a lot of block hash calculations.
- undef 16y agoA single core can hash (checksum) 5 GB/s using murmurhash. The data you checksum is probably already in L1/L2 cache (write to RAID) or going to be used by userland, and us reading the data will just mean userland process gets its data from cache instead (read from RAID). You can get maybe 2-6 GB/s to GPU. Add the latency (sync, etc.) and GPU time to calculate the hash, you've probably radically slowed down the process. Additionally, assuming DMA transfer, your memory subsystem is more stressed due to both CPU and GPU reading same data. Oh, and simple xor? Well, assuming data is in L2 already, Intel i7 can xor 10+ GB/s using just single core, between 3 buffers, aka minimum RAID 5. Fastest RAID adapters can achieve only a fraction of that speed.