Request for review: do not use --sync with df during sanity check

[David Katleman]

Would be interesting to know the original objection to Andrew's change 
last year.

Absent that, I see no reason this could not be removed and the change 
looks fine.

When originally implemented 10+ years ago, disk space was considerably 
smaller, as were buffers, so an accurate count was more relevant.

Today multiple builds on the same disk are fairly common, making the 
check itself even less useful.

Add to that, the information being gathered is just for a WARNING, the 
build will continue, regardless.  Hardly the need for exacting accuracy, 
especially since the df information is then compared to static estimates 
of how much space a build will consume.

             Dave
             (katleman)


On 5/4/2011 2:43 PM, Dr Andrew John Hughes wrote:
> On 17:35 Wed 04 May     , Omair Majid wrote:
>> Hi,
>>
>> Can someone please review the following webrev?
>>
>> http://cr.openjdk.java.net/~omajid/webrevs/no-sync/01/
>>
>> It modifies the sanity check (under linux) to use df without --sync when
>> it computes the free space. This is what is done in the solaris case.
>> The accuracy gained by using --sync is probably not worth the
>> performance loss caused by flushing disk buffers.
>>
>> The patch was originally written by Andrew John Hughes
>> (ahughes at redhat.com) and we have had this in icedtea6 for almost a year now.
>>
>> Thanks,
>> Omair
> Let's see if you do better than I did...
>
> http://mail.openjdk.java.net/pipermail/build-dev/2010-June/003056.html