On Fri, Jul 11, 2014 at 09:26:17AM +1000, Dave Chinner wrote:
> This reverts commit 1f6d64829db78a7e1d63e15c9f48f0a5d2b5a679.
>
> This commit resulted in regressions in performance in low
> memory situations where kswapd was doing writeback of delayed
> allocation blocks. It resulted in significant parallelism of the
> kswapd work and with the special kswapd flags meant that hundreds of
> active allocation could dip into kswapd specific memory reserves and
> avoid being throttled. This cause a large amount of performance
> variation, as well as random OOM-killer invocations that didn't
> previously exist.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> ---
I was going to suggest to keep the bool types, but that's fixed up in
the subsequent patch. ;) Looks good...
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
> fs/xfs/xfs_bmap_util.c | 16 +++-------------
> fs/xfs/xfs_bmap_util.h | 13 ++++++-------
> 2 files changed, 9 insertions(+), 20 deletions(-)
>
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
> index 703b3ec..057f671 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -258,23 +258,14 @@ xfs_bmapi_allocate_worker(
> struct xfs_bmalloca *args = container_of(work,
> struct xfs_bmalloca, work);
> unsigned long pflags;
> - unsigned long new_pflags = PF_FSTRANS;
>
> - /*
> - * we are in a transaction context here, but may also be doing work
> - * in kswapd context, and hence we may need to inherit that state
> - * temporarily to ensure that we don't block waiting for memory reclaim
> - * in any way.
> - */
> - if (args->kswapd)
> - new_pflags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
> -
> - current_set_flags_nested(&pflags, new_pflags);
> + /* we are in a transaction context here */
> + current_set_flags_nested(&pflags, PF_FSTRANS);
>
> args->result = __xfs_bmapi_allocate(args);
> complete(args->done);
>
> - current_restore_flags_nested(&pflags, new_pflags);
> + current_restore_flags_nested(&pflags, PF_FSTRANS);
> }
>
> /*
> @@ -293,7 +284,6 @@ xfs_bmapi_allocate(
>
>
> args->done = &done;
> - args->kswapd = current_is_kswapd();
> INIT_WORK_ONSTACK(&args->work, xfs_bmapi_allocate_worker);
> queue_work(xfs_alloc_wq, &args->work);
> wait_for_completion(&done);
> diff --git a/fs/xfs/xfs_bmap_util.h b/fs/xfs/xfs_bmap_util.h
> index 075f722..935ed2b 100644
> --- a/fs/xfs/xfs_bmap_util.h
> +++ b/fs/xfs/xfs_bmap_util.h
> @@ -50,13 +50,12 @@ struct xfs_bmalloca {
> xfs_extlen_t total; /* total blocks needed for xaction */
> xfs_extlen_t minlen; /* minimum allocation size (blocks) */
> xfs_extlen_t minleft; /* amount must be left after alloc */
> - bool eof; /* set if allocating past last extent */
> - bool wasdel; /* replacing a delayed allocation */
> - bool userdata;/* set if is user data */
> - bool aeof; /* allocated space at eof */
> - bool conv; /* overwriting unwritten extents */
> - bool stack_switch;
> - bool kswapd; /* allocation in kswapd context */
> + char eof; /* set if allocating past last extent */
> + char wasdel; /* replacing a delayed allocation */
> + char userdata;/* set if is user data */
> + char aeof; /* allocated space at eof */
> + char conv; /* overwriting unwritten extents */
> + char stack_switch;
> int flags;
> struct completion *done;
> struct work_struct work;
> --
> 2.0.0
>
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