3 ms·

Couldn't they dump out the list of all individual write commands sent to the disk and have seen that the writes are in a suboptimal pattern? This would have bee

Couldn't they dump out the list of all individual write commands sent to the disk and have seen that the writes are in a suboptimal pattern? This would have been one of the first things I would have done when testing a file system of any kind: Make sure the thing writes what I want to be written and in the way I want it to be written.

forgottenacc57 10y ago
Many problems have obvious solutions in hindsight.
josh64 10y ago
Isn't NCQ meant to do this? I mean reorder the write commands into an optimal order.
koverstreet 10y ago
You don't even need to do anything that hard. All you need to is run basic benchmarks and compare the results to what other filesystems can do, and when yours is about half as fast that should make you go "huh"...
- rurban 10y ago
  Hammer is twice as fast, not half. So huh
  - sleepychu 10y ago
    So it'll now be 4x?
    - rurban 10y ago
      We need benchmarks, and this is the old version only.
cat199 10y ago
People write bugs occasionally. You're talking about the person who spent months tracking down what everyone else thought was a code or compiler bug but actually proved was a subtle CPU bug requiring vendor errata releases, and further, who wrote this log-structured, snapshottable, syncable low-memory using, real-world filesystem from scratch for the highly parallel operating system he has been rearchitecting for over 10 years now. There are consistent status update posts outlining the on disk filesystem structure, as well as its relation to the virtual memory subsystem and the in-kernel parallelism feeding IO writes, as well as constant code commits implementing these things, so I'd reserve the need to back-seat drive here unless I could back it up with a comparable body of work. http://www.theregister.co.uk/2012/03/07/amd_opteron_bug_dragonfly/ http://www.theregister.co.uk/2012/03/07/amd_opteron_bug_drag...

forgottenacc57 10y ago

Many problems have obvious solutions in hindsight.

josh64 10y ago

Isn't NCQ meant to do this? I mean reorder the write commands into an optimal order.

koverstreet 10y ago

You don't even need to do anything that hard. All you need to is run basic benchmarks and compare the results to what other filesystems can do, and when yours is about half as fast that should make you go "huh"...

rurban 10y ago
Hammer is twice as fast, not half. So huh
- sleepychu 10y ago
  So it'll now be 4x?
  - rurban 10y ago
    We need benchmarks, and this is the old version only.

cat199 10y ago

People write bugs occasionally. You're talking about the person who spent months tracking down what everyone else thought was a code or compiler bug but actually proved was a subtle CPU bug requiring vendor errata releases, and further, who wrote this log-structured, snapshottable, syncable low-memory using, real-world filesystem from scratch for the highly parallel operating system he has been rearchitecting for over 10 years now. There are consistent status update posts outlining the on disk filesystem structure, as well as its relation to the virtual memory subsystem and the in-kernel parallelism feeding IO writes, as well as constant code commits implementing these things, so I'd reserve the need to back-seat drive here unless I could back it up with a comparable body of work. http://www.theregister.co.uk/2012/03/07/amd_opteron_bug_dragonfly/ http://www.theregister.co.uk/2012/03/07/amd_opteron_bug_drag...