Hi Dmitry! On Fri, 26 Feb 2010, Dmitry Monakhov wrote: > > Kernels: > > * 2.6.18-164.11.1.el5 x86_64 (latest CentOS 5.4 kernel) > > * 2.6.18-190.el5 x86_64 (latest Red Hat EL5 test kernel I've found from > > http://people.redhat.com/jwilson/el5/ which contains an ext4 version > > which (according to the rpm's changelog) was updated from the 2.6.32 > > ext4 codebase. > Hmm.. It is hard to predict differences between vanilla tree. > This is no only ext4 related. writeback path is changed dramatically. > It is not easy to port writeback code to 2.6.18 with full performance > improvements but without introducing new issues. > > * I did not try a vanilla kernel so far. > IMHO It would be really good to know vanilla kernel's stats. I did a quick&dirty compilation of vanilla kernel 2.6.33 and repeated the test: # /usr/bin/time bash -c "dd if=/dev/zero of=/mnt/large/10GB bs=1M count=10000 && sync" 10000+0 records in 10000+0 records out 10485760000 bytes (10 GB) copied, 50.044 seconds, 210 MB/s 0.01user 13.76system 1:04.75elapsed 21%CPU (0avgtext+0avgdata 6224maxresident)k 0inputs+0outputs (0major+1049minor)pagefaults 0swaps => The problem shows only with the CentOS / Red Hat 5.4 kernels (including RH's test kernel 2.6.18-190.el5). Aadmittedly ext4 is only a technology preview in 5.4... I've also tried the latest CentOS 5.3 kernel-2.6.18-128.7.1.el5 but couldn't mount the device (with -t ext4dev). 2.6.18-164.el5 (the initial CentOS 5.4 kernel) has the bug, too. I'm willing to test patches if somebody wants to debug the problem. -- Karsten Weiss -- 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
