2022-11-21 10:02:15

by Petr Vorel

[permalink] [raw]
Subject: Re: [LTP] [PATCH 1/1] zram01.sh: Workaround division by 0 on vfat on ppc64le

Hi Li,

> Hi Petr,

> On Tue, Nov 8, 2022 at 3:12 AM Petr Vorel <[email protected]> wrote:

> > Repeatedly read /sys/block/zram*/mm_stat for 1 sec. This should fix bug
> > on ppc64le on stable kernels, where mem_used_total is often 0.

> > Signed-off-by: Petr Vorel <[email protected]>
> > ---
> > .../kernel/device-drivers/zram/zram01.sh | 27 +++++++++++++++++--
> > 1 file changed, 25 insertions(+), 2 deletions(-)

> > diff --git a/testcases/kernel/device-drivers/zram/zram01.sh
> > b/testcases/kernel/device-drivers/zram/zram01.sh
> > index 58d233f91..76a8ccab4 100755
> > --- a/testcases/kernel/device-drivers/zram/zram01.sh
> > +++ b/testcases/kernel/device-drivers/zram/zram01.sh
> > @@ -105,6 +105,26 @@ zram_mount()
> > tst_res TPASS "mount of zram device(s) succeeded"
> > }

> > +read_mem_used_total()
> > +{
> > + echo $(awk '{print $3}' $1)
> > +}
> > +
> > +# Reads /sys/block/zram*/mm_stat until mem_used_total is not 0.
> > +loop_read_mem_used_total()


> This is not a looping function to check if mem_used_total is equal to zero,
> the loop part is by means of the TST_RETRY_FUNC macro.
Thanks for your review!

> So, I'd suggest renaming it to check_read_mem_used_total().
Agree. Unfortunately even this didn't help on ppc64le system where I was able to
reproduce it, thus probably not worth to merge.

Unfortunately later I was not able to reproduce the problem any more, I'll try
it more this week.

Kind regards,
Petr

> Reviewed-by: Li Wang <[email protected]>



> > +{
> > + local file="$1"
> > + local mem_used_total
> > +
> > + tst_res TINFO "$file"
> > + cat $file >&2
> > +
> > + mem_used_total=$(read_mem_used_total $file)
> > + [ "$mem_used_total" -eq 0 ] && return 1
> > +
> > + return 0
> > +}
> > +
> > zram_fill_fs()
> > {
> > local mem_used_total
> > @@ -133,9 +153,12 @@ zram_fill_fs()
> > continue
> > fi

> > - mem_used_total=`awk '{print $3}'
> > "/sys/block/zram$i/mm_stat"`
> > + TST_RETRY_FUNC "loop_read_mem_used_total
> > /sys/block/zram$i/mm_stat" 0
> > + mem_used_total=$(read_mem_used_total
> > /sys/block/zram$i/mm_stat)
> > + tst_res TINFO "mem_used_total: $mem_used_total"
> > +
> > v=$((100 * 1024 * $b / $mem_used_total))
> > - r=`echo "scale=2; $v / 100 " | bc`
> > + r=$(echo "scale=2; $v / 100 " | bc)

> > if [ "$v" -lt 100 ]; then
> > tst_res TFAIL "compression ratio: $r:1"
> > --
> > 2.38.0


> > --
> > Mailing list info: https://lists.linux.it/listinfo/ltp