On Mon, 2008-11-24 at 16:44 +0100, Jiri Palecek wrote:
> On Sunday 16 November 2008 12:49:29 CAI Qian wrote:
> > Hi,
> >
> >
> >
> > ----- Original Message ----
> >
> > > From: Jiri Palecek <[EMAIL PROTECTED]>
> > > To: [EMAIL PROTECTED]
> > > Cc: [EMAIL PROTECTED]
> > > Sent: Sunday, November 16, 2008 7:13:39 PM
> > > Subject: Re: [LTP] [PATCH] pipeio - number of writes overflow
> > >
> > > On Saturday 15 November 2008 07:42:59 CAI Qian wrote:
> > > > Hi,
> > > >
> > > > --- On Wed, 11/12/08, Subrata Modak wrote:
> > > > > On Wed, 2008-11-12 at 00:41 +0100, Jiří Paleček wrote:
> > > > > > the computation of the number of writes in pipeio can
> > > > > > overflow, eg. if you
> > > > > > want to run more than 4 GB through the pipe. The
> > > > > > attached patch fixes that.
> > > > >
> > > > > Thanks for this.
> > > >
> > > > It can still overflow after applying the patch.
> > >
> > > Yes; but not if the result is in range.
> > >
> > > > ../pipeio -s 5000 -i 2000000000 -c 5
> > > >
> > > > pipeio 0 INFO : adjusting i/o size to 4096, and # of writes to
> > > > -1853561046 pipeio 1 PASS : 1 PASS 1 pipe reads complete, read
> > > > size = 4096, named pipe, non-blking, pipeio 0 INFO : adjusting
> > > > i/o size to 4096, and # of writes to -1853561046 pipeio 1 FAIL :
> > > > child pipe open(tpipe.4735, 04001) failed: No such file or directory
> > > > pipeio 2 FAIL : Test failed
> > > > pipeio 0 INFO : adjusting i/o size to 4096, and # of writes to
> > > > -1853561046 pipeio 1 FAIL : child pipe open(tpipe.4735, 04001)
> > > > failed: No such file or directory pipeio 2 FAIL : Test failed
> > > > pipeio 0 INFO : adjusting i/o size to 4096, and # of writes to
> > > > -1853561046 pipeio 1 FAIL : child pipe open(tpipe.4735, 04001)
> > > > failed: No such file or directory pipeio 2 FAIL : Test failed
> > > > pipeio 0 INFO : adjusting i/o size to 4096, and # of writes to
> > > > -1853561046 pipeio 1 FAIL : child pipe open(tpipe.4735, 04001)
> > > > failed: No such file or directory pipeio 2 FAIL : Test failed
> > > >
> > > > The following modification made the overflow goes away.
> > > >
> > > > @@ -409,7 +409,7 @@
> > > > */
> > > > if ( size > PIPE_BUF && num_wrters > 1 ) {
> > > > if ( ! loop ) {
> > > > - j=((long long)num_writes*size+PIPE_BUF-1)/PIPE_BUF;
> > > > + j=(int)((long long)num_writes*size+PIPE_BUF-1)/PIPE_BUF;
> > > > num_writes=j;
> > > > tst_resm (TINFO, "adjusting i/o size to %d, and # of
> > > > writes to %d", PIPE_BUF, num_writes);
> > > >
> > > > pipeio 0 INFO : adjusting i/o size to 4096, and # of writes to
> > > > 321322 pipeio 0 INFO : adjusting i/o size to 4096, and # of
> > > > writes to 321322 ....
> > >
> > > No, it doesn't. Your change basically reverts my, but the problem
> > > persists. You didn't want to run 300k writes (per writer) through the
> > > pipe, but 2441406250 writes which is more than INT_MAX (on 32bit
> > > systems), so you got the negative number (the failure is caused by a
> > > different thing, namely, the parent not waiting for children). It would
> > > probably be appropriate to fix this by making j unsigned, but I'm not
> > > sure if someone wanting more than 4G writes would not emerge, closely
> > > followed by someone wanting more than 16P writes :-)
> >
> > That makes sense. It is also possible to have a check with INT_MAX in the
> > test case for the overflowing beforehand to make the test more robust.
>
> OK. I have implemented such a patch. However, I could not test it, because
>
> pipeio -s 5000 -i 2000000000 -c 5
>
> just runs too long.
>
> Regards
> Jiri Palecek
>
Thanks.
Regards--
Subrata
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