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From: Artem Bityutskiy <dedekind1@gmail.com>
To: Matthias Schniedermeyer <ms@citd.de>
Cc: "Luká? Czerner" <lczerner@redhat.com>,
	"Bernd Schubert" <bernd.schubert@itwm.fraunhofer.de>,
	"Dave Chinner" <david@fromorbit.com>,
	"Thomas Knauth" <thomas.knauth@gmx.de>,
	"David Rientjes" <rientjes@google.com>,
	"Maksym Planeta" <mcsim.planeta@gmail.com>,
	"Alexander Viro" <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sysctl: Add a feature to drop caches selectively
Date: Fri, 27 Jun 2014 12:08:14 +0300	[thread overview]
Message-ID: <1403860094.3954.6.camel@sauron.fi.intel.com> (raw)
In-Reply-To: <20140627084139.GA29704@citd.de>

On Fri, 2014-06-27 at 10:41 +0200, Matthias Schniedermeyer wrote:
> On 26.06.2014 13:57, Luká? Czerner wrote:
> 
> > > So if the authors want to sell this new interface (in whatever form) to
> > > the kernel community, they should start with providing a solid use-case,
> > > with some more details, explore alternatives and show how the
> > > alternatives do not work for them.
> > 
> > Yes please, let's see some solid use-case for this.
> 
> Personally i would want it to verify files after copying them:
> Especially while moving files:
> - Copy a file
> - <drop cache>
> - Verify that it really is correct on stable storage
> - Remove original file

To make 100% sure you'd not only need to drop VFS-level caches but also
file-system-level caches. Indeed, file-systems have their own rather
buffers for different indexing data-structures, etc. The unmount/mount
sequence takes care of that.

-- 
Best Regards,
Artem Bityutskiy


WARNING: multiple messages have this Message-ID (diff)
From: Artem Bityutskiy <dedekind1@gmail.com>
To: Matthias Schniedermeyer <ms@citd.de>
Cc: "Luká? Czerner" <lczerner@redhat.com>,
	"Bernd Schubert" <bernd.schubert@itwm.fraunhofer.de>,
	"Dave Chinner" <david@fromorbit.com>,
	"Thomas Knauth" <thomas.knauth@gmx.de>,
	"David Rientjes" <rientjes@google.com>,
	"Maksym Planeta" <mcsim.planeta@gmail.com>,
	"Alexander Viro" <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sysctl: Add a feature to drop caches selectively
Date: Fri, 27 Jun 2014 12:08:14 +0300	[thread overview]
Message-ID: <1403860094.3954.6.camel@sauron.fi.intel.com> (raw)
In-Reply-To: <20140627084139.GA29704@citd.de>

On Fri, 2014-06-27 at 10:41 +0200, Matthias Schniedermeyer wrote:
> On 26.06.2014 13:57, Luká? Czerner wrote:
> 
> > > So if the authors want to sell this new interface (in whatever form) to
> > > the kernel community, they should start with providing a solid use-case,
> > > with some more details, explore alternatives and show how the
> > > alternatives do not work for them.
> > 
> > Yes please, let's see some solid use-case for this.
> 
> Personally i would want it to verify files after copying them:
> Especially while moving files:
> - Copy a file
> - <drop cache>
> - Verify that it really is correct on stable storage
> - Remove original file

To make 100% sure you'd not only need to drop VFS-level caches but also
file-system-level caches. Indeed, file-systems have their own rather
buffers for different indexing data-structures, etc. The unmount/mount
sequence takes care of that.

-- 
Best Regards,
Artem Bityutskiy

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  parent reply	other threads:[~2014-06-27  9:08 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-06-24 16:10 [PATCH] sysctl: Add a feature to drop caches selectively Maksym Planeta
2014-06-24 21:59 ` David Rientjes
2014-06-25  6:25   ` Artem Bityutskiy
2014-06-25  8:25     ` Thomas Knauth
2014-06-25  9:56       ` Artem Bityutskiy
2014-06-25 13:23         ` Thomas Knauth
2014-06-25 13:30           ` Artem Bityutskiy
2014-06-25 13:42           ` Artem Bityutskiy
2014-06-26  9:30             ` Maksym Planeta
2014-06-25 10:03       ` Artem Bityutskiy
2014-06-25 13:19         ` Thomas Knauth
2014-06-25 22:15       ` Pavel Machek
2014-06-26  1:06       ` Dave Chinner
2014-06-26  6:13         ` Artem Bityutskiy
2014-06-26 10:36           ` Bernd Schubert
2014-06-26 11:31             ` Artem Bityutskiy
2014-06-26 11:57               ` Lukáš Czerner
2014-06-26 12:10                 ` Bernd Schubert
2014-06-27  2:55                   ` Dave Chinner
2014-06-27  2:55                     ` Dave Chinner
2014-06-27  8:58                     ` Bernd Schubert
2014-06-27  8:41                 ` Matthias Schniedermeyer
2014-06-27  9:04                   ` Lukáš Czerner
2014-06-27  9:08                   ` Artem Bityutskiy [this message]
2014-06-27  9:08                     ` Artem Bityutskiy
2014-06-27  9:09                     ` Bityutskiy, Artem
2014-06-27  9:09                       ` Bityutskiy, Artem
2014-06-27  2:48           ` Dave Chinner
     [not found] <CACVxJT_6sp=KDy=jCNBypYapKv_59W8LxFU4OiJEm6gt_SuZKg@mail.gmail.com>
2014-06-25 11:21 ` Alexey Dobriyan

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