On Fri, Jun 29, 2007 at 10:23:03AM -0700, Arjan van de Ven wrote: > Stefan Seyfried wrote: > >Holy cow, NO! > >Laptop mode kills performance badly, even the performance of a NFS mount. > > do you have any real data on this? > (and I mean on JUST kernel laptop mode; not any of the other stuff the laptop > mode scripts poke at)
It was some kernels ago, when i wondered wy my copying from / to NFS was only running at less than 5MB/second. I then did "echo 0 > laptop_mode" (was set to 1 or 2) and it immediately increased to the usual >10MB/sec. The dirty_ratio stuff etc. was kept unchanged. I need to retry this with a recent kernel. > >And with my measurements showing that disk spindown has more psychological > >than real powersaving effects on modern laptop drives, i'd say we should > >not do it unless the users asks for "kill my performance badly for a few > >minutes more battery lifetime". > > laptop mode does not spin down the disk. But usually people use it to get their disk to actually spin down. > laptop mode will save real power with ALPM; keeping the sata link idle longer > helps; an idle sata link saves about 1W. This might be true, i did not think about SATA. 1W from the controller is twice as much than what you can get by spinning down the disk. So if it can actually be useful, i need to reevaluate the performance impact i had seen. -- Stefan Seyfried QA / R&D Team Mobile Devices | "Any ideas, John?" SUSE LINUX Products GmbH, Nürnberg | "Well, surrounding them's out." This footer brought to you by insane German lawmakers: SUSE Linux Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg) _______________________________________________ Pm-utils mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/pm-utils
