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Message-ID: <20130711011011.GU3438@dastard> Date: Thu, 11 Jul 2013 11:10:12 +1000 From: Dave Chinner <david@...morbit.com> To: Dmitry Monakhov <dmonakhov@...nvz.org> Cc: xfs@....sgi.com, linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org, dchinner@...hat.com Subject: Re: [PATCH 2/4] large-fs: improve space diversification for ext4 On Tue, Jul 09, 2013 at 03:05:16PM +0400, Dmitry Monakhov wrote: > Currently we allocated several giant files one by one until limit, > so empty space is located as one chunk which limit code-path coverage. > This patch consume all space with NUM_SPACE_FILES files (by default 1024) > each has same size, and when truncate each one by required delta. > As result we have $NUM_SPACE_FILES chunks of free blocks distributed > across whole filesystem. > This should help us to avoid regressions similar to e7c9e3e99adf6c49 Sounds like a good idea - distributing free space around the filesystem - but why limit this to ext4? If you turn this into a generic "largefs fill space" function, it will work just as well with XFS as it does for ext4, and with any other filesystem that we want to support --largefs testing on.... I'd also add a CLI option to check to set NUM_SPACE_FILES like we do for LARGE_SCRATCH_DEV and SCRATCH_DEV_EMPTY_SPACE. I'd probably also call it SCRATCH_DEV_EMPTY_SPACE_FILES.... > Signed-off-by: Dmitry Monakhov <dmonakhov@...nvz.org> > --- > common/rc | 40 ++++++++++++++++------------------------ > 1 files changed, 16 insertions(+), 24 deletions(-) > > diff --git a/common/rc b/common/rc > index c44acea..902fc19 100644 > --- a/common/rc > +++ b/common/rc > @@ -440,12 +440,17 @@ _setup_large_ext4_fs() > fs_empty_space=$((50*1024*1024*1024)) > > [ "$LARGE_SCRATCH_DEV" != yes ] && return 0 > + [ -z "$NUM_SPACE_FILES" ] && export NUM_SPACE_FILES=1024 > [ -z "$SCRATCH_DEV_EMPTY_SPACE" ] && SCRATCH_DEV_EMPTY_SPACE=0 > fs_empty_space=$((fs_empty_space + $SCRATCH_DEV_EMPTY_SPACE)) > [ $fs_empty_space -ge $fs_size ] && return 0 > > # calculate the size of the file we need to allocate. > + > space_to_consume=$(($fs_size - $fs_empty_space)) > + file_size_falloc=$(($fs_size/$NUM_SPACE_FILES)) > + file_size_final=$(($space_to_consume/$NUM_SPACE_FILES)) spaces around "/" > + > # mount the filesystem and create 16TB - 4KB files until we consume > # all the necessary space. > _scratch_mount 2>&1 >$tmp_dir/mnt.err > @@ -457,33 +462,20 @@ _setup_large_ext4_fs() > return $status > fi > rm -f $tmp_dir/mnt.err > - > - file_size=$((16*1024*1024*1024*1024 - 4096)) > - nfiles=0 > - while [ $space_to_consume -gt $file_size ]; do > - > + mkdir $SCRATCH_MNT/.use_space > + # Consume all space on filesytem > + for ((nfiles = 0; nfiles < nfiles_total; nfiles++)); do Is that bashism supported on older versions of bash? i.e. like the versions found on RHEL5, SLES10, etc? If not, then a simple: for nfiles in `seq 0 1 $nfiles_total`; do will work just as well.... > xfs_io -F -f \ change that to XFS_IO_PROG and we can drop the -F there. > - -c "truncate $file_size" \ > - -c "falloc -k 0 $file_size" \ > - $SCRATCH_MNT/.use_space.$nfiles 2>&1 > - status=$? > - if [ $status -ne 0 ]; then > - break; > - fi > - > - space_to_consume=$(( $space_to_consume - $file_size )) > - nfiles=$(($nfiles + 1)) > + -c "truncate $file_size_falloc" \ > + -c "falloc -k 0 $file_size_falloc" \ > + $SCRATCH_MNT/.use_space/use_space.$nfiles 2>&1 Is there any need for the truncate + falloc -k? I can't remember why I did that in the first place. Just a "falloc 0 $file_size_falloc" shoul dbe sufficient, right? > done > - > - # consume the remaining space. > - if [ $space_to_consume -gt 0 ]; then > + # Truncate files to smaller size, will free chunks of space > + for ((nfiles = 0; nfiles < nfiles_total; nfiles++)); do > xfs_io -F -f \ Same again for XFS_IO_PROG. Cheers, Dave. -- Dave Chinner david@...morbit.com -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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