Messages in this thread |  | | Date | Wed, 26 Sep 2001 06:38:48 -0700 (MST) | From | Craig Kulesa <> | Subject | VM in 2.4.10(+tweaks) vs. 2.4.9-ac14/15(+stuff) |
| |
As requested, here are a number of tests of the latest VM patches. Tests are described in a previous post, archived here:
http://www.uwsg.indiana.edu/hypermail/linux/kernel/0109.3/0033.html
Results:
2.4.10 performance is great compared to 2.4.[7-9], but these tests still seem to point out some room for improvement in the 2.4.10 VM tree. 2.4.10 and 2.4.10(+00_vm-tweaks-1) performed similarly. The vm-tweaks patch improved the swap smoothness, but the number of pages swapped out didn't change measurably, nor did the large number of swap-ins. Clogging the system with dirty pages via 'dd' still causes XMMS to skip badly.
Let's push the aging/list-order code more by driving the system a bit harder in step d), namely adding mozilla to the common user application test. We will also stream mp3 audio throughout the entire test.
2.4.10(+00_vm-tweaks-1) 48 sec StarOffice load time 28 sec 2560x2560 GIMP image rotation 82400 KB swapped out, 92148 KB swapped back in
2.4.9-ac14 + aging 33 sec StarOffice load time 25 sec GIMP image rotation 30072 KB swapped out, 22252 KB swapped back in
2.4.9-ac15 + aging + launder 33 sec StarOffice load time 24 sec GIMP image rotation 57556 KB swapped out, 25900 KB swapped back in
'vmstat 1' sessions for these three cases are available at: http://loke.as.arizona.edu/~ckulesa/kernel/
2.4.10+ is clearly working a LOT harder to keep dentry and inode caches in memory, and is swapping out harder to compensate. The ac14/ac15 tree frees those caches more freely, and don't page application working sets out so readily.
Let's test this statement by not pre-filling the inode and dentry caches with 'slocate' and performing the same test:
2.4.10(+00_vm-tweaks) 26 sec StarOffice load time 24 sec GIMP image rotation 48332 KB swapped out, 33521 KB swapped back in
2.4.9-ac14 + aging 32 sec StarOffice load time 26 sec GIMP image rotation 37392 KB swapped out, 11952 KB swapped back in
2.4.9-ac15 + aging + launder 32 sec StarOffice load time 22 second GIMP image rotation 23884 KB swapped out, 10828 KB swapped back in
2.4.10 does much better this time; in particular the StarOffice loading that was so plagued by swapouts, pressured by dentry/inode caching last time, went smoothly. But there's still more paging than with 2.4.9-ac1[4-5].
Let's try one more aging/list-order experiment. Instead of creating a 2560x2560 GIMP image first, then loading StarOffice and many other applications after (to start swapping, and cause GIMP pages to be candidates for reaping) -- this time let's load StarOffice first and then create the GIMP image. This should keep the GIMP image at a 'younger' age and presumably shouldn't page back into memory (rotation should be faster). StarOffice may swap itself entirely out however.
2.4.10(+00_vm-tweaks) 25 sec StarOffice load time 29 sec GIMP image rotation 64427 KB swapped out, 77422 KB swapped back in
2.4.9-ac14 + aging 30 sec StarOffice load time 24 sec GIMP image rotation 22147 KB swapped out, 8922 swapped back in
2.4.9-ac15 + aging + launder 31 sec StarOffice load time 21 second GIMP image rotation 17204 KB swapped out, 8224 swapped back in
The 2.4.10 behavior surprised me. The GIMP pages are younger in memory, yet the rotation was slowed by swapin & swapout activity -- slower than before. Plus more StarOffice pages were swapped out, so it had to be paged back in order to close the application. I'm puzzled. The ac14/ac15 behavior was closer to what I expected; the GIMP pages were young and unswapped, only the earliest StarOffice pages had to be recalled.
These are samples of rather 'ordinary' loads which 2.4.10 needs some work handling; the ac15 tree is doing a better job with this particular set right now (ac15 tree also doesn't skip XMMS with the creation of lots of dirty pages via 'dd'). But all three kernels tested kept the user interface relatively responsive, which is an improvement over previous 2.4 releases. Very cool.
A note on page_launder(). ac14 has the smoothest swapping, with small chunks laundered at a time. ac14+aging and ac15+aging+launder both swap out huge (10-20 MB) chunks at a time. Admittedly, the user interface is responsive and XMMS doesn't skip a beat, but most of the 60 MB of actual swapout in the first test in ac15+stuff came from only THREE lines of 'vmstat 1' output. Otherwise there was no swapout activity.
Best regards, and thanks for the excellent work!
Craig Kulesa Steward Observatory, Univ. of Arizona
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |