On 05/05/14 10:40, Dirk Behme wrote: > Hi, > > regarding boot time optimization, on an embedded ARM Cortex-A9 based > system with 512MB or 1GB main memory, we found that initializing this > main memory takes a somehow large amount of time. > > Initializing 512MB takes <= ~100ms, the additional 512MB on the 1GB take > <= ~100ms additionally, too. So in sum <= ~200ms for 1GB. > > Having a short look to this, it looks like most of the time is spent in > arch/arm/mm/init.c in bootmem_init()/arm_bootmem_init()/arm_bootmem_free(). > > Has anybody already looked into this if there are any optimizations > possible? Maybe even some hacks, if the main memory size (512MB/1GB) is > always known? Any pointers? There were a couple of longish threads last year. Random links into the middle of 'em: http://www.spinics.net/lists/linux-mm/msg54027.html http://lkml.iu.edu//hypermail/linux/kernel/1306.3/01915.html > I'm looking for reducing (a) the overall init time and maybe (b) the > dependency on the memory size. Basically they were deferring init by abusing the hotplug mechanism, so the system started with less memory and a background thread added more of it. Rob -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
