Re: [patch] radix-tree: avoid atomic allocations for preloaded insertions

[David Miller <davem@davemloft.net>]

> Why not just stomp the warning with __GFP_NOWARN?
> 
> Did you consider turning off __GFP_HIGH?  (Dunno why)
> 
> This change will slow things down - has this been quantified?  Probably
> it's unmeasurable, but it's still there.
> 
> I'd have thought that a superior approach would be to just set
> __GFP_NOWARN?

I've rerun my test case which triggers this on Niagara 2
and I no longer get the messages.

For reference I first create N 16GB sparse files with
a script such as:

#!/bin/sh
#
# Usage: create_sparse NUM_FILES

for i in $(seq $1)
do
   dd if=/dev/zero of=sparse_file_$i bs=1MB count=1 seek=$((16 * 1024))
done

And then I fork off N threads, each running dd over one of
those sparse files with a script like:

#!/bin/sh
#
# Usage: thread_sparse NUM_THREADS

for i in $(seq $1)
do
    dd bs=1M if=sparse_file_$i of=/dev/null &
done

wait

On my Niagara 2 box I use '64' for 'N', so I go:

create_sparse 64
thread_sparse 64

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