On Mon, Aug 22, 2016 at 2:11 AM, Hannes Reinecke <hare@xxxxxxx> wrote: > On 08/22/2016 06:34 AM, Shaun Tancheff wrote: >> Currently the RB-Tree zone cache is fast and flexible. It does >> use a rather largish amount of ram. This model reduces the ram >> required from 120 bytes per zone to 16 bytes per zone with a >> moderate transformation of the blk_zone_lookup() api. >> >> This model is predicated on the belief that most variations >> on zoned media will follow a pattern of using collections of same >> sized zones on a single device. Similar to the pattern of erase >> blocks on flash devices being progressivly larger 16K, 64K, ... >> >> The goal is to be able to build a descriptor which is both memory >> efficient, performant, and flexible. >> >> Signed-off-by: Shaun Tancheff <shaun.tancheff@xxxxxxxxxxx> >> --- >> block/blk-core.c | 2 +- >> block/blk-sysfs.c | 31 +- >> block/blk-zoned.c | 103 +++-- >> drivers/scsi/sd.c | 5 +- >> drivers/scsi/sd.h | 4 +- >> drivers/scsi/sd_zbc.c | 1025 +++++++++++++++++++++++++++--------------------- >> include/linux/blkdev.h | 82 +++- >> 7 files changed, 716 insertions(+), 536 deletions(-) > Have you measure the performance impact here? As far as actual hardware (HostAware) I am seeing the same I/O performance. I suspect its just that below 100k iops the zone cache just isn't a bottleneck. > The main idea behind using an RB-tree is that each single element will > fit in the CPU cache; using an array will prevent that. > So we will increase the number of cache flushes, and most likely a > performance penalty, too. > Hence I'd rather like to see a performance measurement here before going > down that road. I think it will have to be a simulated benchmark, if that's okay. Of course I'm open to suggestions if there is something you have in mind. -- Regards, Shaun Tancheff -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
