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Message-ID: <20140820020924.GD32620@bbox>
Date: Wed, 20 Aug 2014 11:09:24 +0900
From: Minchan Kim <minchan@...nel.org>
To: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc: Chao Yu <chao2.yu@...sung.com>, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, ngupta@...are.org,
'Jerome Marchand' <jmarchan@...hat.com>,
'Andrew Morton' <akpm@...ux-foundation.org>
Subject: Re: [PATCH] zram: add num_discards for discarded pages stat
Hi Sergey,
On Tue, Aug 19, 2014 at 08:25:00PM +0900, Sergey Senozhatsky wrote:
> Hello,
>
> On (08/19/14 13:45), Chao Yu wrote:
> > > On (08/15/14 11:27), Chao Yu wrote:
> > > > Now we have supported handling discard request which is sended by filesystem,
> > > > but no interface could be used to show information of discard.
> > > > This patch adds num_discards to stat discarded pages, then export it to sysfs
> > > > for displaying.
> > > >
> > >
> > > a side question: we account discarded pages via slot free notify in
> > > notify_free and via req_discard in num_discards. how about accounting
> > > both of them in num_discards? because, after all, they account a number
> > > of discarded pages (zram_free_page()). or there any particular reason we
> > > want to distinguish.
> >
> > Yeah, I agree with you as I have no such reason unless there are our users'
> > explicitly requirement for showing notify_free/num_discards separately later.
> >
> > How do you think of sending another patch to merge these two counts?
> >
>
> Minchan, what do you think? let's account discarded pages in one place.
First of all, I'd like to know why we need num_discards.
It should be in description and depends on it whether we should merge both
counts or separate.
Thanks.
>
> > One more thing is that I am missing to update document of zram, sorry about
> > that, let me update it in v2.
>
> thanks.
>
> -ss
>
> > Thanks,
> > Yu
> >
> > >
> > > -ss
> > >
> > > > Signed-off-by: Chao Yu <chao2.yu@...sung.com>
> > > > ---
> > > > Documentation/ABI/testing/sysfs-block-zram | 10 ++++++++++
> > > > drivers/block/zram/zram_drv.c | 3 +++
> > > > drivers/block/zram/zram_drv.h | 1 +
> > > > 3 files changed, 14 insertions(+)
> > > >
> > > > diff --git a/Documentation/ABI/testing/sysfs-block-zram
> > > b/Documentation/ABI/testing/sysfs-block-zram
> > > > index 70ec992..fa8936e 100644
> > > > --- a/Documentation/ABI/testing/sysfs-block-zram
> > > > +++ b/Documentation/ABI/testing/sysfs-block-zram
> > > > @@ -57,6 +57,16 @@ Description:
> > > > The failed_writes file is read-only and specifies the number of
> > > > failed writes happened on this device.
> > > >
> > > > +
> > > > +What: /sys/block/zram<id>/num_discards
> > > > +Date: August 2014
> > > > +Contact: Chao Yu <chao2.yu@...sung.com>
> > > > +Description:
> > > > + The num_discards file is read-only and specifies the number of
> > > > + physical blocks which are discarded by this device. These blocks
> > > > + are included in discard request which is sended by filesystem as
> > > > + the blocks are no longer used.
> > > > +
> > > > What: /sys/block/zram<id>/max_comp_streams
> > > > Date: February 2014
> > > > Contact: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> > > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> > > > index d00831c..904e7a5 100644
> > > > --- a/drivers/block/zram/zram_drv.c
> > > > +++ b/drivers/block/zram/zram_drv.c
> > > > @@ -606,6 +606,7 @@ static void zram_bio_discard(struct zram *zram, u32 index,
> > > > bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
> > > > zram_free_page(zram, index);
> > > > bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
> > > > + atomic64_inc(&zram->stats.num_discards);
> > > > index++;
> > > > n -= PAGE_SIZE;
> > > > }
> > > > @@ -866,6 +867,7 @@ ZRAM_ATTR_RO(num_reads);
> > > > ZRAM_ATTR_RO(num_writes);
> > > > ZRAM_ATTR_RO(failed_reads);
> > > > ZRAM_ATTR_RO(failed_writes);
> > > > +ZRAM_ATTR_RO(num_discards);
> > > > ZRAM_ATTR_RO(invalid_io);
> > > > ZRAM_ATTR_RO(notify_free);
> > > > ZRAM_ATTR_RO(zero_pages);
> > > > @@ -879,6 +881,7 @@ static struct attribute *zram_disk_attrs[] = {
> > > > &dev_attr_num_writes.attr,
> > > > &dev_attr_failed_reads.attr,
> > > > &dev_attr_failed_writes.attr,
> > > > + &dev_attr_num_discards.attr,
> > > > &dev_attr_invalid_io.attr,
> > > > &dev_attr_notify_free.attr,
> > > > &dev_attr_zero_pages.attr,
> > > > diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
> > > > index e0f725c..2994aaf 100644
> > > > --- a/drivers/block/zram/zram_drv.h
> > > > +++ b/drivers/block/zram/zram_drv.h
> > > > @@ -86,6 +86,7 @@ struct zram_stats {
> > > > atomic64_t num_writes; /* --do-- */
> > > > atomic64_t failed_reads; /* can happen when memory is too low */
> > > > atomic64_t failed_writes; /* can happen when memory is too low */
> > > > + atomic64_t num_discards; /* no. of discarded pages */
> > > > atomic64_t invalid_io; /* non-page-aligned I/O requests */
> > > > atomic64_t notify_free; /* no. of swap slot free notifications */
> > > > atomic64_t zero_pages; /* no. of zero filled pages */
> > > > --
> > > > 2.0.1.474.g72c7794
> > > >
> > > >
> > >
> > > --
> > > To unsubscribe, send a message with 'unsubscribe linux-mm' in
> > > the body to majordomo@...ck.org. For more info on Linux MM,
> > > see: http://www.linux-mm.org/ .
> > > Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a>
> >
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
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> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a>
--
Kind regards,
Minchan Kim
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