On Thu, Sep 04, 2014 at 09:04:48PM +0800, Zheng Liu wrote: > > I thought the reason why we have the EXT4_GET_BLOCKS_NO_PUT_HOLE flag > > is because in ext4_da_map_blocks(), if there is a hole, we will be > > immediately following it up with a call to ext4_es_insert_extent() to > > fill in the hole with the EXTENT_STATUS_DELAYED flag. The only time > > we don't is if we run into an ENOSPC error. > > > > Am I missing something? > > Yes, you are right. The purpose is used to do the work like you said > above. As the commit log described this flag brings a huge number of > cache misses when an empty file is written. Right, and I was trying to figure out why that was happening, because it looked like in the normal case we would immediately fill in the hole afterwards. I was goign to try doing some tracing to understand why this was resulting a huge number of cache misses, but I haven't had time to do that investigation yet. Can you sketch out the scenario where this was leading to so many cache misses? Thanks, - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
