Hi Jerry, I think you make a good recommendation, explaining the issue of write back via cache vs. immediately hitting the disk. I also think your mail explains why we should not change the default. Instead, lets change the documentation, to explain that those not needing consistency can use this performance optimization. Jon. -- Sent from my iPad On Jan 11, 2013, at 10:42, Jerry James <loganjerry@xxxxxxxxx> wrote: > I've been using the vexpress image with QEMU to try to track down some > ARM-specific problems in two of my packages. The VM was unbearably > slow at first (by which I mean that a simple "yum upgrade" took over 6 > hours), until I changed: > > -sd "$IMAGE" > > to: > > -drive if=sd,cache=writeback,file="$IMAGE" > > in boot-vexpress and boot-vexpress+x. I'm well aware of the danger of > using writeback, but ... it's a VM. With the script as shipped, my > hard drive light was on constantly, and the entire host was slowed > down dramatically due to insufficient disk bandwidth. With writeback > on, I can re-create the VM and reinstall the packages of interest in > very little time, certainly less than even simple operations were > taking with write-through on. Is there some reason why changing the > scripts to use writeback would not be a good idea? > > Regards, > -- > Jerry James > http://www.jamezone.org/ > _______________________________________________ > arm mailing list > arm@xxxxxxxxxxxxxxxxxxxxxxx > https://admin.fedoraproject.org/mailman/listinfo/arm _______________________________________________ arm mailing list arm@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/arm
