On (08/12/14 16:37), Minchan Kim wrote:
> On Mon, Aug 11, 2014 at 04:39:17PM +0800, Chao Yu wrote:
> > Since we allocate a temporary buffer in zram_bvec_read to handle partial
> > page
> > operations in this commit 924bd88d703e53d30f393fac6117f8f1bc79aab6 (Staging:
> > zram: allow partial page operations), our ->failed_reads value may be
> > incorrect
> > as we do not increase its value when failed to allocate the temporary
> > buffer.
> >
> > Let's fix this issue and correct the annotation of failed_reads.
>
> Good catch.
> Just out of curiosity.
>
> Did you catch it by code review or real workload?
>
> >
> > Signed-off-by: Chao Yu <chao2...@samsung.com>
> > ---
> > drivers/block/zram/zram_drv.c | 1 +
> > drivers/block/zram/zram_drv.h | 2 +-
> > 2 files changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> > index dfa4024..bf8ea1b 100644
> > --- a/drivers/block/zram/zram_drv.c
> > +++ b/drivers/block/zram/zram_drv.c
> > @@ -413,6 +413,7 @@ static int zram_bvec_read(struct zram *zram, struct
> > bio_vec *bvec,
> >
> > if (!uncmem) {
> > pr_info("Unable to allocate temp memory\n");
> > + atomic64_inc(&zram->stats.failed_reads);
> > ret = -ENOMEM;
> > goto out_cleanup;
> > }
> > diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
> > index 5b0afde..e0f725c 100644
> > --- a/drivers/block/zram/zram_drv.h
> > +++ b/drivers/block/zram/zram_drv.h
> > @@ -84,7 +84,7 @@ struct zram_stats {
> > atomic64_t compr_data_size; /* compressed size of pages stored */
> > atomic64_t num_reads; /* failed + successful */
> > atomic64_t num_writes; /* --do-- */
> > - atomic64_t failed_reads; /* should NEVER! happen */
> > + atomic64_t failed_reads; /* can happen when memory is too low */
> > atomic64_t failed_writes; /* can happen when memory is too low */
> > atomic64_t invalid_io; /* non-page-aligned I/O requests */
> > atomic64_t notify_free; /* no. of swap slot free notifications */
> > --
> > 2.0.1.474.g72c7794
>
> How abouting moving failed_reads/writes in zram_bvec_rw?
>
> int zram_bvec_rw(..)
> {
> if (rw == READ) {
> atomic64_inc(num_reads);
> ret = zram_bvec_read(xxx);
> } else {
> atomic64_inc(&num_writes);
> ret = zram_bvec_write(xxx);
> }
>
> if (unlikely(ret)) {
> if (rw == READ)
> atomic64_inc(failed_reads);
> else
> atomic64_inc(failed_writes);
> }
> }
>
looks good. these stats were supposed to be here.
-ss
> >
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majord...@vger.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at http://www.tux.org/lkml/
>
> --
> Kind regards,
> Minchan Kim
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
