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From: Fengguang Wu <fengguang.wu@intel.com>
To: Jan Kara <jack@suse.cz>
Cc: Tejun Heo <tj@kernel.org>, Jens Axboe <axboe@kernel.dk>,
	linux-kernel@vger.kernel.org, chavey@google.com
Subject: Re: [PATCH v2] writeback: mark sysctl vm.block_dump for removal
Date: Wed, 16 Jan 2013 10:53:26 +0800	[thread overview]
Message-ID: <20130116025326.GB10000@localhost> (raw)
In-Reply-To: <20130116020753.GB25806@quack.suse.cz>

On Wed, Jan 16, 2013 at 03:07:53AM +0100, Jan Kara wrote:
> On Tue 15-01-13 08:28:13, Tejun Heo wrote:
> > vm.block_dump is nasty in that it dumps IO traces directly to printk.
> > It isn't scalable and can easily lead to looping behavior - IO
> > generating kernel message which in turn genreates log IO, ad
> > infinitum.
> > 
> > Now that proper tracepoints are in place, vm.block_dump isn't
> > necessary.  Generate a warning if used so that it can be removed down
> > the road.

> > +	if (!warned && block_dump) {
> > +		pr_warning("sysctl: vm.block_dump is scheduled for removal. Use tracepoints instead.\n");
> > +		pr_warning("sysctl: Please contact Jens Axboe <axboe@kernel.dk> if you require this.\n");
> > +		warned = true;

Looks good to me. A warning in dmesg is pertinent because the
block_dump users will be looking at dmesg for block dump results.

Hmm, perhaps a more practical tip on the usage of replacement
tracepoints or tool will help eliminate some user emails to Jens.

> > diff --git a/patches/series b/patches/series
> > index 9fb9bfe..b2582cb 100644
> > --- a/patches/series
> > +++ b/patches/series
> > @@ -18,3 +18,4 @@ kill-pool-gcwq
> >  remove-gcwq
> >  rename-nr_running
> >  cleanup-leftovers
> > +dbg

An extra chunk.

Reviewed-by: Fengguang Wu <fengguang.wu@intel.com>

Thanks!

      reply	other threads:[~2013-01-16  2:53 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-01-11 21:06 [PATCHSET] block: improve tracepoints, take#2 Tejun Heo
2013-01-11 21:06 ` [PATCH 1/5] block: add missing block_bio_complete() tracepoint Tejun Heo
2013-01-11 21:06 ` [PATCH 2/5] block: add @req to bio_{front|back}_merge tracepoints Tejun Heo
2013-01-11 21:06 ` [PATCH 3/5] buffer: make touch_buffer() an exported function Tejun Heo
2013-01-11 21:06 ` [PATCH 4/5] block: add block_{touch|dirty}_buffer tracepoint Tejun Heo
2013-01-11 21:06 ` [PATCH 5/5] writeback: add more tracepoints Tejun Heo
2013-01-12  3:17   ` Fengguang Wu
2013-01-14 13:57     ` Jan Kara
2013-01-14 14:02 ` [PATCHSET] block: improve tracepoints, take#2 Jens Axboe
2013-01-14 17:43   ` Tejun Heo
2013-01-14 18:22     ` [PATCH] writeback: mark sysctl vm.block_dump for removal Tejun Heo
2013-01-14 19:00       ` Jan Kara
2013-01-15 16:28       ` [PATCH v2] " Tejun Heo
2013-01-16  2:07         ` Jan Kara
2013-01-16  2:53           ` Fengguang Wu [this message]

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