On Mon, 14 May 2001, Ben LaHaise wrote:

Hey folks,

Hi. 

The patch below consists of 3 seperate fixes for helping remove the
deadlocks present in current kernels with respect to highmem systems.
Each fix is to a seperate file, so please accept/reject as such.

<snip>

The third patch (to vmscan.c) adds a SCHED_YIELD to the page launder code
before starting a launder loop.  This one needs discussion, but what I'm
attempting to accomplish is that when kswapd is cycling through
page_launder repeatedly, bdflush or some other task submitting io via the
bounce buffers needs to be given a chance to run and complete their io
again.  Failure to do so limits the rate of progress under extremely high
load when the vast majority of io will be transferred via bounce buffers.

Your patch may allow bdflush or some other task to submit IO if kswapd is
looping mad --- but it will not avoid kswapd from eating all the CPU
time, which is the _main_ problem. 

If we avoid kswapd from doing such a thing (which is what we should try to
fix in the first place), there is no need for your patch.


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