Hello Ted, On Mon, Jan 14, 2013 at 09:48:00AM -0500, Theodore Ts'o wrote: > Hi, > > The Linux Foundation's Collaboration Summit is April 15-17th, > and the Linux Storage, File System, and MM Summit is April 18-19th in > San Francisco (at the Parc 55 hotel). > > I'd like to organize an ext4 developer's meeting during the > Collab Summit sometime April 15-17th, since so many of us will hopefully > be attending LSF. (The CFP will hopefully be coming soon for LSF.) > > If you're interested in attending, please reply to this thread, > and include some suggested topics that you'd be interested in > discussing. Based on the number of topics and the number of people who > are planning on attending, I'll know how much time we need to reserve > and how big of a room to request. > > Also, if you need a invitation letter for Visa purposes, also > please let me know. I can arrange for the Linux Foundation to get that > letter sent, so that folks have enough time to get a Visa. Tao and I would like to attend the ext4 workshop this year. Here are some topics that we want to discuss with other folks at this meeting. * Optimization for different devices We can consume more resources (e.g. Memory) for Flash/SSD device to get a better performance. Meanwhile we want to reduce the consumption and provide a best effort performance for HDD in a low-end server with a ARM CPU, only 1G memory, and 4 x 3T disks. This are two different directions of optimization. * Stable tree and long-term tree I remember that Ted has talked about ext4 stable and long-term tree. So we can discuss in this meeting how to maintain them and other detail. * Extent tree disk layout In this mail [1], Ted metioned that extent structure could be extented to support larger file, such as 64-bits physical block, bigger logical block, and using cluster-size as unit in extent. All these can make us better support large filesystem. 1. http://comments.gmane.org/gmane.comp.file-systems.ext4/35490 * Block allocation hint An interface (e.g. ioctl(2)) is provided to let the app give a block allocation hint. Filesystem can allocate some blocks that can be read/written faster than other blocks for a file, such as allocating blocks on outter track in HDD. * Latency Chris had presented a proposal that is 'data=guarded', which aims at imporving the latency of sync. We can discuss how to provide stable latency in ext4. Forgive me that I compare two filesystems here, but the result of the following test case shows that the latency of ext4 is higher than xfs's. So maybe we can improve it. I use 'fio' to do the following test. I revert the patches of stable page write for avoiding the impact of it. Meanwhile I disable delalloc feature in ext4. I repeat the test case serveral times, but the result of ext4 is higher than xfs. [global] iodepth=1 directory=/mnt/sda3 direct=0 group_reporting thread fallocate=0 runtime=120 [log-append] ioengine=sync rw=write bs=4k size=10g filesize=10g rate=5m numjobs=1 I pick the best result of two filesystems and paste them here. [ext4] write: io=614404KB, bw=5119.2KB/s, iops=1279 , runt=120001msec clat (usec): min=11 , max=149 , avg=14.12, stdev= 1.73 lat (usec): min=11 , max=150 , avg=14.54, stdev= 1.81 [xfs] write: io=614404KB, bw=5119.2KB/s, iops=1279 , runt=120001msec clat (usec): min=4 , max=89 , avg= 8.42, stdev= 1.85 lat (usec): min=4 , max=89 , avg= 8.80, stdev= 1.94 BTW, Tao and I need a invitation letter for applying our visa. Please let me know if there are something we need to do. Thanks, - Zheng -- 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
