Messages in this thread |  | | Date | Tue, 18 Sep 2001 22:18:54 +0200 | From | Andrea Arcangeli <> | Subject | Re: 2.4.10-pre11: alsaplayer skiping during kernel build (-pre10 did not) |
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On Tue, Sep 18, 2001 at 01:02:27PM -0700, Andrew Morton wrote: > Andrea Arcangeli wrote: > > > > I now have an update ready for Linus to merge that should fix the few > > leftovers I had in the very first release of the vm rewrite but of > > course I will be interested to hear about any regression/progression > > about those changes, I'll post them in a few minutes in CC to l-k. > > > > Please include Andi's likely()/unlikely() change - it's nice.
I guess I'll postpone the likely/unlikely after resynching with Linus since I'm basically ready to run rsync and I prefer to go sleep early today and to think about new things tomorrow ;).
I also have a few arguments about the likely/unlikely to solve before agreeing on it, in particular in all my usages the value will be either 0 or 1 so I don't see why should I tell gcc to do !!, probably it will be optimized away but I also don't see why should the left term matter for an "if", the "if" only cares about zero or non zero, so I should be able to define the fast path with an 1 even if my result is 2, otherwise it sounds like gcc is doing something strange.
> I can't measure any obviously new causes of latency in your > VM. It's nice that you've paid attention to this in various > places.
thanks.
> The main culprits now are the file IO and dirty buffer writeout paths: > up to fifty milliseconds in each. > > I suggest you stick scheduling points in generic_file_read(), > generic_file_write() and write_locked_buffers() and then dispose > of the copy-user-latency patch from -aa kernels.
Yes, I pretty much agree on such change, I remeber you just pointed out once. It's postponed to tomorrow too ;).
At the moment I just care to post the vm fixes against pre11 plain in order to possibly get some feedback on it while I sleep :)
> With the above fixed, the main source of latency is > /proc/meminfo->si_swapinfo(). It's about five milliseconds per gig > of swap, which isn't too bad. But it's directly invokable by > userspace (ie: /usr/bin/top) and really should be made less dumb.
ok.
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