On Sat, May 28, 2011 at 12:56:40AM -0700, Andrew Morton wrote: > On Fri, 27 May 2011 18:01:28 +0530 Ankita Garg <ankita@xxxxxxxxxx> wrote: > > > This patchset proposes a generic memory regions infrastructure that can be > > used to tag boundaries of memory blocks which belongs to a specific memory > > power management domain and further enable exploitation of platform memory > > power management capabilities. > > A couple of quick thoughts... > > I'm seeing no estimate of how much energy we might save when this work > is completed. But saving energy is the entire point of the entire > patchset! So please spend some time thinking about that and update and > maintain the [patch 0/n] description so others can get some idea of the > benefit we might get from all of this. That estimate should include an > estimate of what proportion of machines are likely to have hardware > which can use this feature and in what timeframe. > > IOW, if it saves one microwatt on 0.001% of machines, not interested ;) FWIW, I have seen estimates on the order of a 5% reduction in power consumption for some common types of embedded devices. Thanx, Paul > Also, all this code appears to be enabled on all machines? So machines > which don't have the requisite hardware still carry any additional > overhead which is added here. I can see that ifdeffing a feature like > this would be ghastly but please also have a think about the > implications of this and add that discussion also. > > If possible, it would be good to think up some microbenchmarks which > probe the worst-case performance impact and describe those and present > the results. So others can gain an understanding of the runtime costs. > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>