On Thursday 18 May 2006 17:11, Nick Piggin wrote:
If we're under memory pressure, kswapd will try to free up any candidate
zone, yes.
On my test case this indeed happens and my ZONE_DMA never goes below 3000
pages free. If I lower the reserve even further my pages free gets stuck
at 3208 and can't free any more, and doesn't ever drop below that either.
Here is the patch I was proposing
What problem does that fix though?
It's a generic concern and I honestly don't know how significant it is which is why I'm asking if it needs attention. That concern being that any time we're under any sort of memory pressure, ZONE_DMA will undergo intense reclaim even though there may not really be anything specifically going on in ZONE_DMA. It just seems a waste of cycles doing that.