Messages in this thread | | | Date | Tue, 25 Dec 2007 14:05:26 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH 0/4] add task handling notifier |
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On Sun, 23 Dec 2007 12:26:21 +0000 Christoph Hellwig <hch@infradead.org> wrote:
> On Thu, Dec 20, 2007 at 01:11:24PM +0000, Jan Beulich wrote: > > With more and more sub-systems/sub-components leaving their footprint > > in task handling functions, it seems reasonable to add notifiers that > > these components can use instead of having them all patch themselves > > directly into core files. > > I agree that we probably want something like this. As do some others, > so we already had a few a few attempts at similar things. The first one > is from SGI and called PAGG (http://oss.sgi.com/projects/pagg/) and also > includes allocating per-task data for it's users. Then also from SGI > there has been a simplified version called pnotify that's also available > from the website above. > > Later Matt Helsley had something called "Task Watchers" which lwn has > an article on: http://lwn.net/Articles/208117/. > > For some reason neither ever made a lot of progess (performance > problems?). >
I had it in -mm, sorted out all the problems but ended up not pulling the trigger.
Problem is, it adds runtime overhead purely for the convenience of kernel programmers, and I don't think that's a good tradeoff.
Sprinkling direct calls into a few well-known sites won't kill us, and we've survived this long. Why not keep doing that, and save everyone a few cycles?
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