On Thu, Oct 04, 2007 at 03:07:18PM -0700, David Miller wrote: > From: Chuck Ebbert <cebbert@xxxxxxxxxx> Date: Thu, 04 Oct 2007 17:47:48 > -0400 > > > On 10/04/2007 05:11 PM, David Miller wrote: > > > From: Chuck Ebbert <cebbert@xxxxxxxxxx> Date: Thu, 04 Oct 2007 17:02:17 > > > -0400 > > > > > >> How do you simulate reading 100TB of data spread across 3000 disks, > > >> selecting 10% of it using some criterion, then sorting and summarizing > > >> the result? > > > > > > You repeatedly read zeros from a smaller disk into the same amount of > > > memory, and sort that as if it were real data instead. > > > > You've just replaced 3000 concurrent streams of data with a single stream. > > That won't test the memory allocator's ability to allocate memory to many > > concurrent users very well. > > You've kindly removed my "thinking outside of the box" comment. > > The point is was not that my specific suggestion would be perfect, but that > if you used your creativity and thought in similar directions you might find > a way to do it. > > People are too narrow minded when it comes to these things, and that's the > problem I want to address. And it's a good point, too, because often problems to one person are a no-brainer to someone else. Creating lots of "fake" disks is trivial to do, IMO. Use loopback on sparse files containing sparse filesxi, use ramdisks containing sparse files or write a sparse dm target for sparse block device mapping, etc. I'm sure there's more than the few I just threw out... Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
