On 17 August 2012 09:36, Kent Overstreet <koverstreet@xxxxxxxxxx> wrote: > On Thu, Aug 16, 2012 at 10:07:29PM +1000, Joseph Glanville wrote: >> There also seems to have been pretty severe performance regressions in >> cache bypassed sequential I/O. >> The newer code barely does 70mb/s sequential writes when >> sequential_cuttoff is set to 4M however it does around 300mb/s when >> set to 0 (no bypass) with dd and 1M block size. >> When using the older codebase the cache bypass is actually slightly >> faster than going to cache at around 360mb/s but this is still much >> slower than the underlying block devices (as previously discussed). > > Ouch. Can you try profiling it with perf while running dd? > > perf record -afg dd etc. etc. > perf report > > should do it Sure can. -- CTO | Orion Virtualisation Solutions | www.orionvm.com.au Phone: 1300 56 99 52 | Mobile: 0428 754 846 -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
