> 在 2018年4月10日，下午1:38，Amir Goldstein <amir73il@xxxxxxxxx> 写道： > > On Tue, Apr 10, 2018 at 4:29 AM, cgxu519@xxxxxxx <cgxu519@xxxxxxx> wrote: >> Hi guys, >> >> I’m a little curious for below code in ovl_lookup, is there any background for >> copy stack instead of directly using it? >> >> memcpy(oe->lowerstack, stack, sizeof(struct ovl_path) * ctr); >> > > Memory compaction. > > stack has ofs->numlower entries, which could be very large, > but after lookup, oe->numlower can end up being much much > smaller. Also, ovl_alloc_entry() packs lowerstack together with > ovl_entry, so the overall memory usage of the long lived overlay > dentry cache entries is lower. For regular file the maximum numlower is 1, so for optimizing memory allocation/free maybe we can put one ovl_path entry inside ovl_entry and allocate/deallocate ovl_entry via cache pool and for dir we can link to ovl_path array from ovl_entry. Does it make sense? Thanks, Chengguang. -- To unsubscribe from this list: send the line "unsubscribe linux-unionfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
