Re: [RFC -mm] memcg: prevent from OOM with too many dirty pages

[Johannes Weiner]

On Thu, Jun 07, 2012 at 04:45:56PM +0200, Michal Hocko wrote:
> On Fri 01-06-12 10:37:30, Michal Hocko wrote:
> [...]
> > More detailed statistics (max/min - the worst/best performance).
> > 	comparison (cong is 100%)	comparison (page reclaim 100%)			
> > 	max	min	median		max	min	median
> > * ext3
> > ** Write
> > 5M	171.20%	95.33%	98.70%		216.96%	101.99%	103.61%
> > 60M	97.56%	98.80%	104.51%		110.09%	100.11%	116.59%
> > 300M	99.76%	99.49%	99.35%		99.47%	99.89%	99.57%
> > 2G	99.52%	99.53%	99.52%		100.09%	99.07%	100.02%
> > 
> > ** Read					
> > 5M	35.37%	38.70%	39.09%		83.55%	89.85%	86.54%
> > 60M	89.70%	102.90%	102.00%		97.71%	101.91%	102.06%
> > 300M	92.38%	99.33%	99.14%		80.65%	98.39%	91.23%
> > 2G	90.07%	99.92%	100.38%		99.85%	100.75%	99.94%
> > 
> > * Tmpfs					
> > ** write
> > 5M	121.85%	99.69%	131.57%		219.22%	99.85%	135.30%
> > 60M	140.82%	99.70%	139.57%		98.14%	54.51%	73.65%
> > 300M	97.99%	99.54%	99.60%		99.29%	99.57%	99.32%
> > 2G	99.37%	99.62%	99.64%		98.72%	99.92%	99.18%
> > 
> > ** read				
> > 5M	85.44%	92.96%	88.92%		129.13%	101.54%	97.87%
> > 60M	64.41%	94.35%	88.10%		97.41%	95.75%	96.31%
> > 300M	116.89%	106.52%	120.84%		132.17%	104.39%	130.63%
> > 2G	86.27%	99.96%	87.47%		60.69%	99.44%	98.49%
> 
> I have played with the patch below but it didn't show too much
> difference in the end or we end up doing even worse. 
> 
> Here is the no_patch/patched comparison:
> 
> 	comparison (page reclaim is 100%)
> * ext3  avg	max	min	median
> ** Write
> 5M    	81.49%	77.53%	101.91%	76.60%
> 60M   	98.60%	95.58%	101.40%	99.62%
> 300M  	101.68%	102.05%	101.19%	101.73%
> 2G    	102.20%	102.25%	102.12%	102.22%
> 				
> ** Read  				
> 5M    	103.94%	105.14%	103.95%	103.32%
> 60M   	105.26%	107.91%	103.15%	104.95%
> 300M  	104.83%	107.86%	101.65%	104.88%
> 2G    	102.67%	101.26%	102.83%	103.35%
> 
> * Tmpfs
> ** Write
> 5M    	107.68%	119.66%	105.26%	102.78%
> 60M   	122.16%	138.51%	103.62%	121.09%
> 300M  	101.03%	100.67%	101.11%	101.17%
> 2G    	101.82%	101.66%	101.87%	101.87%
> 				
> ** Read			
> 5M    	102.47%	124.02%	98.05%	92.57%
> 60M   	103.62%	121.03%	96.97%	96.52%
> 300M  	98.90%	118.92%	102.64%	86.19%
> 2G    	83.50%	76.34%	97.36%	81.92%
> 
> I am not sure it really makes sense to play with the priority here. All
> the values we would end up with would be just wild guesses or mostly
> artificial workloads. So I think it makes some to go with the original
> version of the PageReclaim patch without any further fiddling with the
> priority.
> 
> Is this sufficient to go with the patch or do people still have concerns
> which would block the patch from merging?

No, let's go for it.  It's a net improvement as it stands.

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
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