Messages in this thread |  | | | Date | Tue, 27 Jun 2006 15:07:16 +0200 | | From | Helge Hafting <> | | Subject | New readahead - ups and downs |
| |
Many have noticed positive sides of the new readahead system. I too see that, bootup is quicker and starting a big app like firefox is also noticeable faster.
I made my own little io-intensive test, that shows a case where performance drops.
I boot the machine, and starts "debsums", a debian utility that checksums every file managed by debian package management. As soon as the machine starts swapping, I also start start a process that applies an mm-patch to the kernel tree, and times this.
This patching took 1m28s with cold cache, without debsums running. With the 2.6.15 kernel (old readahead), and debsums running, this took 2m20s to complete, and 360kB in swap at the worst.
With the new readahead in 2.6.17-mm3 I get 6m22s for patching, and 22MB in swap at the most. Runs with mm1 and mm2 were similiar, 5-6 minutes patching and 22MB swap.
My patching clearly takes more times this way. I don't know if debsums improved though, it could be as simple as a fairness issue. Memory pressure definitely went up.
Helge Hafting - 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/
|  |