On Sat, Apr 24, 2010 at 1:04 PM, Ric Wheeler <rwheeler@xxxxxxxxxx> wrote: <snip> > > Let's summarize. > > 1. Everyone agrees that doing larger discard instead of little discards is a > good thing. > > 2. Some devices care about this more than others (various types of SSD's and > arrays have different designs and performance with discards). Some devices > do small discards well, others don't. > > 3. How you get to those bigger discards in our implementation - using a > series of single range requests, using vectored requests, tracking extents > that can be combined in an rbtree or not - is something that we are working > on. Using rbtrees versus a bitmap efficiency is about DRAM consumption, not > performance of the resulting discard on the target. > > 4. Devices (some devices) can export their preferences in a standard way > (look in /sys/block/....). > > If you want to influence the code, please do try the various options on > devices you have at hand and report results. That is what we are doing (we > includes Lukas, Eric, Jeff and others on this thread) will real devices from > vendors that have given us access. We are talking to them directly and > trying out different work loads but certainly welcome real world results and > suggestions. > > Thanks! > > Ric Ric, Is it also agreed by all that the current ext4 kernel implementation of calling discard is a poor solution for most hardware / block layers stacks / workloads and therefore is not worth retaining nor performing further benchmarks? I've not seen anyone arguing to keep the current kernel implementation and I for one accept the previously posted benchmarks that show it is not adding any value relative to the traditional non-discard case. Therefore benchmarks between the current hdparm/wiper.sh userspace implementation and a proposed new kernel implementation would be the most beneficial? I have yet to see any of those benchmarks posted. Greg -- Greg Freemyer Head of EDD Tape Extraction and Processing team Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer CNN/TruTV Aired Forensic Imaging Demo - http://insession.blogs.cnn.com/2010/03/23/how-computer-evidence-gets-retrieved/ The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.com -- 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
