Neil Brown <neilb@xxxxxxx> wrote: > > On Sunday April 30, akpm@xxxxxxxx wrote: > > NeilBrown <neilb@xxxxxxx> wrote: > > > > > > > > > When a md array has been idle (no writes) for 20msecs it is marked as > > > 'clean'. This delay turns out to be too short for some real > > > workloads. So increase it to 200msec (the time to update the metadata > > > should be a tiny fraction of that) and make it sysfs-configurable. > > > > > > > > > ... > > > > > > + safe_mode_delay > > > + When an md array has seen no write requests for a certain period > > > + of time, it will be marked as 'clean'. When another write > > > + request arrive, the array is marked as 'dirty' before the write > > > + commenses. This is known as 'safe_mode'. > > > + The 'certain period' is controlled by this file which stores the > > > + period as a number of seconds. The default is 200msec (0.200). > > > + Writing a value of 0 disables safemode. > > > + > > > > Why not make the units milliseconds? Rename this to safe_mode_delay_msecs > > to remove any doubt. > > Because umpteen years ago when I was adding thread-usage statistics to > /proc/net/rpc/nfsd I used milliseconds and Linus asked me to make it > seconds - a much more "obvious" unit. See Email below. > It seems very sensible to me. That's output. It's easier to do the conversion with output. And I guess one could argue that lots of people read /proc files, but few write to them. Generally I don't think we should be teaching the kernel to accept pretend-floating-point numbers like this, especially when a) "delay in milliseconds" is such a simple concept and b) it's so easy to go from float to milliseconds in userspace. Do you really expect that humans (really dumb ones ;)) will be echoing numbers into this file? Or will it mainly be a thing for mdadm to fiddle with? - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
