linux-kernel - Re: EXT4-ish "fixes" in UBIFS

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Date:	Thu, 2 Apr 2009 18:59:27 -0600
From:	"Trenton D. Adams" <trenton.d.adams@...il.com>
To:	Christian Kujau <lists@...dbynature.de>
Cc:	Artem Bityutskiy <Artem.Bityutskiy@...ia.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: EXT4-ish "fixes" in UBIFS

On Thu, Apr 2, 2009 at 6:54 PM, Trenton D. Adams
<trenton.d.adams@...il.com> wrote:
> On Thu, Apr 2, 2009 at 6:38 PM, Christian Kujau <lists@...dbynature.de> wrote:
>> On Thu, 2 Apr 2009, Trenton D. Adams wrote:
>>> I'm thinking of writing a script that monitors performance, and
>>> remounts as needed, lol.  WHAT A HACK. hehe.
>>
>> Ugh....my brain hurts :-\
>>
>> Christian.
>
> Yeah, mine too.
>

Just to make it hurt more for you, here you go...

On one console I run...
dd if=/dev/zero of=/tmp/bigfile bs=1M count=2000

On another I run...
perf-mon.sh
remounting with sync option, performance dropping
remounting without sync option, performance has stabilized

It may be better to write a C program that does a 1M fsync, and if
it's taking too long, then remount, lol.  Also, this script here,
using 1 min load average, will catch CPU intensity as well, which is
not really what I want.  Ah, it is a hack indeed. ROFL

#!/bin/sh

while true; do
    UPTIME=$(uptime | xargs | cut -d ' ' -f10 | sed 's/,//');
    if [ "$(echo "$UPTIME > 1" | bc)" -eq "1" ]; then
        mount | egrep 's-sys.*sync' >/dev/null
        if [ "$?" -ne "0" ]; then
            echo "remounting with sync option, performance dropping";
            mount -o remount,rw,sync /dev/s/sys /;
        fi
    else
        mount | egrep 's-sys.*sync' > /dev/null
        if [ "$?" -eq "0" ]; then
            echo "remounting without sync option, performance has stabilized";
            mount -o remount,rw /dev/s/sys /;
        fi
    fi;
    sleep 1
done
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