Re: vim file write mode on journaling fs.

[Steve Lord <lord@sgi.com>]

> Steve Lord <lord@sgi.com> writes:
> 
> >   2. An individual thread doing a write in XFS has no way of knowing
> >   or predicting what else may just of happened, or be about to
> >   happen on the system. You cannot say 'I will write my data now
> >   because the system is idle', there may be a couple of Gbytes of
> >   I/O about to come in from another source.
> 
> Why couldn't the kernel keep some statistics about disk usage, and use
> those to make an educated guess as to whether or not we should write
> out the data immediately?

This is a main kernel thing, not an XFS thing. Look at all the back and
forth about the VM subsystem in 2.4, people are writing code which works
in their environment, it gets into the kernel, then someone else says their
performance tanked. It is the same sort of issue, this type of thing is
very hard to get right in a manner which pleases everyone.

Steve