Re: [RFC][PATCH] mm: cut down __GFP_NORETRY page allocation failures

[Wu Fengguang <fengguang.wu@intel.com>]

Andrew,

I tested the more realistic 100 dd case. The results are

- nr_alloc_fail: 892 => 146
- reclaim delay: 4ms => 68ms

Thanks,
Fengguang
---

base kernel, 100 dd
-------------------

start time: 3
total time: 52
nr_alloc_fail 892
allocstall 131341

2nd run (no reboot):

start time: 3
total time: 53
nr_alloc_fail 1555
allocstall 265718


CPU             count     real total  virtual total    delay total
                  962     3125524848     3113269116    37972729582
IO              count    delay total  delay average
                    3       25204838              8ms
SWAP            count    delay total  delay average
                    0              0              0ms
RECLAIM         count    delay total  delay average    
                 1032     5130797747              4ms  

(IPIs accumulated in two runs)
CAL:      34898      35428      35182      35553      35320      35291      35298      35102   Function call interrupts

10ms limit, 100 dd
------------------

start time: 2
total time: 50
nr_alloc_fail 146
allocstall 10598

CPU             count     real total  virtual total    delay total
                 1038     3349490800     3331087137    40156395960
IO              count    delay total  delay average
                    0              0              0ms
SWAP            count    delay total  delay average
                    0              0              0ms
RECLAIM         count    delay total  delay average
                   84     5795410854             68ms
dd: read=0, write=0, cancelled_write=0

Thanks,
Fengguang