> On Wed, Jun 19, 2002 at 03:50:58PM -0400, Perry E. Metzger wrote:
> > UBC seems to be working fine. What do you think is wrong with it? Or
> > is this your claim that the max/min memory usage sysctls aren't working?
>
> Thew issue when you copy a large file to the same disk as the system disk,
> the system becomes ususable. It's not a problem with UBC per se, it
> the "IO priority" problem I talked about a bit on tech-kern (the I/O
> queue gets filled with writes, and another, small I/O request requires
> seconds to get serviced).
> This is not a problem with UBC per se. I've been fighting with this problem
> on 1.5.2 mail servers (working around by limiting the write rate in
> userland daemons). It's possible that UBC made it worse, though.
>

it made it MUUUCH worse. copying large file under 1.5.2 made no noticable
slowdown of programs like navigator. with 1.6BETA2 even xterm is unusable.


the problem is that UBC does total wipeout of programs code and data. it's
just overagressive. yes write flooding make things worse, but real problem
is that apps need to reread swapped out/deallocated pages.

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Where do you think you go today?