(switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface). hm, that's news to me. Does anyone have access to a large i386 setup? Interested in reproducing this and figuring out what's going wrong? On Thu, 22 Jun 2017 06:25:49 +0000 bugzilla-daemon@xxxxxxxxxxxxxxxxxxx wrote: > https://bugzilla.kernel.org/show_bug.cgi?id=196157 > > Bug ID: 196157 > Summary: 100+ times slower disk writes on 4.x+/i386/16+RAM, > compared to 3.x > Product: Memory Management > Version: 2.5 > Kernel Version: 4.x > Hardware: All > OS: Linux > Tree: Mainline > Status: NEW > Severity: normal > Priority: P1 > Component: Page Allocator > Assignee: akpm@xxxxxxxxxxxxxxxxxxxx > Reporter: alkisg@xxxxxxxxx > Regression: No > > Me and a lot of other users have an issue where disk writes start fast (e.g. > 200 MB/sec), but after intensive disk usage, they end up 100+ times slower > (e.g. 2 MB/sec), and never get fast again until we run "echo 3 > > /proc/sys/vm/drop_caches". > > This issue happens on systems with any 4.x kernel, i386 arch, 16+ GB RAM. > It doesn't happen if we use 3.x kernels (i.e. it's a regression) or any 64bit > kernels (i.e. it only affects i386). > > My initial bug report was in Ubuntu: > https://bugs.launchpad.net/ubuntu/+source/linux-hwe/+bug/1698118 > > I included a test case there, which mostly says "Copy /lib around 100 times. > You'll see that the first copy happens in 5 seconds, and the 30th copy may need > more than 800 seconds". > > Here is my latest version of the script (basically, the (3) step below): > 1) . /etc/os-release; echo -n "$VERSION, $(uname -r), $(dpkg > --print-architecture), RAM="; awk '/MemTotal:/ { print $2 }' /proc/meminfo > 2) mount /dev/sdb2 /mnt && rm -rf /mnt/tmp/lib && mkdir -p /mnt/tmp/lib && sync > && echo 3 > /proc/sys/vm/drop_caches && chroot /mnt > 3) mkdir -p /tmp/lib; cd /tmp/lib; s=/lib; d=1; echo -n "Copying $s to $d: "; > while /usr/bin/time -f %e sh -c "cp -a '$s' '$d'; sync"; do s=$d; > d=$((($d+1)%100)); echo -n "Copying $s to $d: "; done > > And here are some results, where you can see that all 4.x+ i386 kernels are > affected: > ----------------------------------------------------------------------------- > 14.04, Trusty Tahr, 3.13.0-24-generic, i386, RAM=16076400 [Live CD] > 8-13 secs > > 15.04 (Vivid Vervet), 3.19.0-15-generic, i386, RAM=16083080 [Live CD] > 5-7 secs > > 15.10 (Wily Werewolf), 4.2.0-16-generic, i386, RAM=16082536 [Live CD] > 4-350 secs > > 16.04.2 LTS (Xenial Xerus), 3.19.0-80-generic, i386, RAM=16294832 [HD install] > 10-25 secs > > 16.04.2 LTS (Xenial Xerus), 4.2.0-42-generic, i386, RAM=16294392 [HD install] > 14-89 secs > > 16.04.2 LTS (Xenial Xerus), 4.4.0-79-generic, i386, RAM=16293556 [HD install] > 15-605 secs > > 16.04.2 LTS (Xenial Xerus), 4.8.0-54-generic, i386, RAM=16292708 [HD install] > 6-160 secs > > 16.04.2 LTS (Xenial Xerus), 4.12.0-041200rc5-generic, i386, RAM=16292588 [HD > install] > 46-805 secs > > 16.04.2 LTS (Xenial Xerus), 4.8.0-36-generic, amd64, RAM=16131028 [Live CD] > 4-11 secs > > An example single run of the script: > ----------------------------------------------------------------------------- > 16.04.2 LTS (Xenial Xerus), 4.8.0-54-generic, i386, RAM=16292708 [HD install] > ----------------------------------------------------------------------------- > Copying /lib to 1: 37.23 > Copying 1 to 2: 6.74 > Copying 2 to 3: 6.88 > Copying 3 to 4: 7.89 > Copying 4 to 5: 7.91 > Copying 5 to 6: 9.03 > Copying 6 to 7: 8.46 > Copying 7 to 8: 8.10 > Copying 8 to 9: 8.93 > Copying 9 to 10: 10.51 > Copying 10 to 11: 10.33 > Copying 11 to 12: 11.08 > Copying 12 to 13: 11.78 > Copying 13 to 14: 14.18 > Copying 14 to 15: 18.42 > Copying 15 to 16: 23.19 > Copying 16 to 17: 61.08 > Copying 17 to 18: 155.88 > Copying 18 to 19: 141.96 > Copying 19 to 20: 152.98 > Copying 20 to 21: 163.03 > Copying 21 to 22: 154.85 > Copying 22 to 23: 137.13 > Copying 23 to 24: 146.08 > Copying 24 to 25: > > Thank you! > > -- > You are receiving this mail because: > You are the assignee for the bug. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
