On Thu, 2011-01-20 at 10:46 +0800, Andrew Morton wrote: > On Thu, 20 Jan 2011 10:34:18 +0800 Shaohua Li <shaohua.li@xxxxxxxxx> wrote: > > > > > Under a harddisk based netbook with Meego, the metadata readahead > > > > reduced about 3.5s boot time in average from total 16s. > > > > > > That's a respectable speedup. And it *needs* to be a good speedup, > > > given how hacky all of this is! > > > > > > But then.. reducing bootup time on a laptop/desktop/server by 3.5s > > > isn't exactly a world-shattering benefit, is it? Is it worth all the > > > hacky code? > > a laptop/desktop/server need read more data from hard disks, this will > > give more bootup time saving I think, though not tested yet. > > Well, the whole point of the patch is to improve boot times, so the > more boot-time testing you can do, the better that is! each distribution uses its own readahead (data readahead) daemon, it's time-cost to change the daemon, but I'll check if I get some data in a desktop. > > > It would be much more valuable if those 3.5 seconds were available to > > > devices which really really care about bootup times, but very few of > > > those devices use rotating disks nowadays, I expect? > > Currently most popular netbooks are using rotating disks actually. And > > this will benefit laptop/desktop too. > > But my point is that three seconds boot-time improvement for a system > which has an uptime of days or months isn't terribly exciting. > > What *would* be terribly exciting is a three-second improvement for > cameras, cellphones, etc. But they don't use spinning disks. > > Can we expect *any* benefit for flash-type storage devices? If so, how > much? There should be no benefit for high end SSD, because they have high throughput even for random IO. For low end flash-type storage devices, this should have a little benefit, but won't expect much. I can't test a camera or cellphone, I can test a USB disk in a desktop if you like. Thanks, Shaohua -- 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
