Comment 541 for bug 620074

> The actual bug here is
> related to the kernel preferring to evict memory-mapped executable pages when
> a
> process dirties blocks faster than they can be flushed to disk.

Okay.

Let it be so. However, the subject line for this bug is

> Large I/O operations result in poor interactive performance and high iowait
> times

and that's what I'm experiencing now, rsync'ing a 100 GB worth of data with almost everything being there on the receiving side (thus making the receiving rsync read files heavily for the checksums). And I am dead sure this has nothing to do with the virtual memory as the swap is completely off (I would probably need to compile a different kernel with no support for swapping to reconfirm). iowait rises to 90%, LA shows disturbingly large numbers of up to 20, and unrelated processes like Xorg freeze, taking around 15 seconds to redraw the screen or move the mouse cursor or whatever.

What I thought this bug was about is that while one process does overwhelmingly large volumes of I/O, it should by no means impact other, unrelated processes which might not even use the disc subsystem, or not use the same disc. At least this is what Mac OS X does: for example, Transmission preallocates space for 40 GB worth of torrent data, naturally freezing in the process and ceasing to respond to any events, but then again, I can minimise its window, type code in Eclipse or anything — barely noticing the disc thrashing. I think I'm reiterating this example for the upmteenth time here, sorry if that's the case.

If I'm wrong and the bug #12309 was reduced to its VM part, I just request which one is about the above problem — high iowait affecting unrelated processes, with no swapping involved. Is that #13347? I cannot follow it because the submitter uses a dialect of English I'm not quite capable to parse. If there's no specific bug, I'll take the time to report it, because it bugs me a great deal, however I'm afraid I'll have to repeat most of the tests already conducted here.

Please don't take it as if I'm trying to offend anyone, because I'm not. I just want to know where does go the specific symptom as described above.

Thank you all for every effort to have it resolved.