Messages in this thread |  | | Date | Tue, 24 Oct 2000 21:42:56 +0200 | From | Martin Dalecki <> | Subject | Re: PATCH: killing read_ahead[] |
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Jeff Garzik wrote: > > > Please have a look at the following patch and feel free to be scared > > by the fact how UTTERLY BROKEN and ARBITRARY the current usage of the > > read_ahead[] array and during the whole past decade was! > > If you really care about clean internal interfaces this should be > > one of those prio number ONE targets to shoot at... > > > > The most amanzing thing is that the whole test10-pre5 kernel with this > > patch applied doesn't show any performance penalties for me at all! > > And of corse it's about 10k smaller... > > I agree with you and Rik that this array needs to go away... but > ripping out the feature is not the answer, IMHO. > > Can you work up a patch that instead changes the readahead to be a hash > table? The key could be a hash of the blkdev/chrdev pointer value (or > kdev_t for now). Considering the number of users, the hash table can be > pretty darn small for most machines, but we can easily scale its size > dynamically at boot if need be. > > That would give us the per-device granularity we need to actually make > the feature useful, and allow us to kill the hacks you mention in > existing drivers (like the MD and SCSI examples you cited).
A log log time ago (about 2.3.xx) I actually posted a patch which was the preparation for *EXACTLY* this step and which contained a bit of *OBVIOUS* other cleanup. However those times I requested to get a confirmation that if I start to work *SERIOUSLY* on it then it wouldn't be for nothing. I don't intend to spend my spare time on such a thing without knowing IN FRONT that this work won't get ignored due to the IGNORANCE of some person. I didn't get any clean response...
Anyway if you ask whatever I'm able to prepare such a patch the answer is - obviously yes.
PS. This is an general problem of the "Open Source" developement modell - exagerous waiste of resources where many profesionalls don't wan't to be involved with - however if you would dare to invite me to France for a hack session of about 2-3 days I would deligtefully take hollidays from my current job or a prolonged weekend and do it anyway whatever "big L" says (or doesnt say ;-). - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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