Messages in this thread | | | Date | Thu, 2 Apr 2009 18:24:28 -0700 (PDT) | From | david@lang ... | Subject | Re: Ext4 and the "30 second window of death" |
| |
On Fri, 3 Apr 2009, Matthew Garrett wrote:
> On Thu, Apr 02, 2009 at 06:16:20PM -0700, david@lang.hm wrote: >> On Fri, 3 Apr 2009, Matthew Garrett wrote: >> >>> On Thu, Apr 02, 2009 at 05:55:11PM -0700, david@lang.hm wrote: >>>> On Fri, 3 Apr 2009, Matthew Garrett wrote: >>>>> Then they shouldn't use a mail client that fsync()s. >>>> >>>> so they need to use one mail client when they want to have good battery >>>> life and a different one when they are plugged in to power? >>> >>> They need to make a decision about whether they care about their mailbox >>> being precisely in sync with their server or not, and either use a >>> client that adapts appropriately or choose a client that behaves >>> appropriately. It's certainly not the kernel's business. >> >> the kernel is not deciding this, the kernel would be implementing the >> user's choice > > No it wouldn't. The kernel would be implementing an adminstrator's > choice about whether fsync() is important or not. That's something that > would affect the mail client, but it's hardly a decision based on the > mail client. Sucks to be that user if they do anything involving mysql.
in the case of laptops, in 99+% of the cases the user and the administrator are the same person. in the other cases that's something the user should take up with the administrator, because the administrator can do a lot of things to the system that will affect the safety of their data (including loading a kernel that turns fsync into a noop, but more likely involving enabling or disabling write caches on disks)
>>> If you can demonstrate a real world use case where the hard drive >>> (typically well under a watt of power consumption on modern systems) >>> spindown policy will be affected sufficiently pathologically by a mail >>> client that you lose an hour of battery life, then I'd rethink this. But >>> mostly I'd conclude that this was an example of an inappropriate >>> spindown policy. >> >> remember that the mail client was an example. >> >> you want another example, think of anything that uses sqlite (like the >> firefox history stuff, although that was weakened drasticly due to the >> ext3 problems). > > Benchmarks please.
if spinning down a drive saves so little power that it wouldn't make a significant difference to battery lift to leave it on, why does anyone bother to spin the drive down?
David Lang
| |