On Tue, Mar 15, 2011 at 11:44 AM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 15 Mar 2011 11:40:46 +0900 Minchan Kim <minchan.kim@xxxxxxxxx> wrote: > >> On Tue, Mar 15, 2011 at 11:28 AM, Andrew Morton >> <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: >> > On Tue, 15 Mar 2011 11:12:37 +0900 Minchan Kim <minchan.kim@xxxxxxxxx> wrote: >> > >> >> >> I can't understand why we should hanlde activate_page_pvecs specially. >> >> >> Please, enlighten me. >> >> > Not it's special. akpm asked me to do it this time. Reducing little >> >> > memory is still worthy anyway, so that's it. We can do it for other >> >> > pvecs too, in separate patch. >> >> >> >> Understandable but I don't like code separation by CONFIG_SMP for just >> >> little bit enhance of memory usage. In future, whenever we use percpu, >> >> do we have to implement each functions for both SMP and non-SMP? >> >> Is it desirable? >> >> Andrew, Is it really valuable? >> > >> > It's a little saving of text footprint. __It's also probably faster this way - >> > putting all the pages into a pagevec then later processing them won't >> > be very L1 cache friendly. >> > >> > >> >> I am not sure how much effective it is in UP. But if L1 cache friendly >> is important concern, we should not use per-cpu about hot operation. > > It's not due to the percpu thing. ÂThe issue is putting 14 pages into a > pagevec and then later processing them after the older ones might have > fallen out of cache. > >> I think more important thing in embedded (normal UP), it is a lock latency. >> I don't want to hold/release the lock per page. > > There is no lock on UP builds. > I mean _frequent_ irq disable. But I don't want to bother you due to this issue as I said. It's up to you. If you merge the path as-is, I will help to clean up remained-things. But at least, in my point, I don't want to add frequent irq disable. -- Kind regards, Minchan Kim -- 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