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On 12/04/11 11:27, Alan Jenkins wrote:
On 12/03/11 22:58, Lucas De Marchi wrote:
We are almost complete now: parsing the config, looking up modules, inserting and deleting modules. We still need to handle dependencies when inserting and deleting but our priority now is to optimize the lookup stuff, caching the config/indexes when we start, etc. I welcome you to contribute to this lib if you are interested. Regards, Lucas De Marchi
Thanks for working on this. I may be able to provide some feedback.
One nitpick:
I'm not sure caching the /indexes/, as a whole, would be worth it.
1. Hopefully we benefit from the page cache, and the now-ubiquitous boot prefetch implementations. [Although using stdio with the default buffer size probably means we copy several times more data than necessary. See setvbuf()].
2. Caching the root index node sounds nice - don't know whether it'd be measurably useful.
3. mmap() might work to avoid copying completely. I avoided it for modprobe; my understanding was that for a one-shot command it would probably be slower. Also the current indexes aren't stored in host byte order, and the code relies on copying to keep things simple.
I would avoid switching to mmap() without good evidence. In general, my approach would be to leave the core of index.c alone, because it scares me :). The other two points would be reasonably small tweaks.
Alan
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