On Tue, Jun 14, 2011 at 20:30, Arnd Bergmann <arnd@xxxxxxxx> wrote: > On Tuesday 14 June 2011 18:58:35 Michal Nazarewicz wrote: >> Ah yes, I forgot that separate regions for different purposes could >> decrease fragmentation. > > That is indeed a good point, but having a good allocator algorithm > could also solve this. I don't know too much about these allocation > algorithms, but there are probably multiple working approaches to this. imo no allocator algorithm is gonna help if you have comparably large, variable-sized contiguous allocations out of a restricted address range. It might work well enough if there are only a few sizes and/or there's decent headroom. But for really generic workloads this would require sync objects and eviction callbacks (i.e. what Thomas Hellstrom pushed with ttm). So if this is only a requirement on very few platforms and can be cheaply fixed with multiple cma allocation areas (heck, we have slabs for the same reasons in the kernel), it might be a sensible compromise. -Daniel -- Daniel Vetter daniel.vetter@xxxxxxxx - +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- 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>