From: Vladimir Murzin <murzin.v@gmail.com>
To: Dan Streetman <ddstreet@ieee.org>
Cc: linux-mm@kvack.org, Seth Jennings <sjennings@variantweb.net>,
linux-kernel <linux-kernel@vger.kernel.org>,
Bob Liu <bob.liu@oracle.com>, Minchan Kim <minchan@kernel.org>,
Weijie Yang <weijie.yang@samsung.com>
Subject: Re: [PATCH] mm/zswap: change params from hidden to ro
Date: Fri, 22 Nov 2013 08:38:54 +0100 [thread overview]
Message-ID: <20131122073851.GB1853@hp530> (raw)
In-Reply-To: <CALZtONA81=R4abFMpMMtDZKQe0s-8+JxvEfZO3NEZ910VwRDmw@mail.gmail.com>
On Wed, Nov 20, 2013 at 12:52:47PM -0500, Dan Streetman wrote: > On Wed, Nov
20, 2013 at 12:33 PM, Vladimir Murzin <murzin.v@gmail.com> wrote: > > Hi Dan!
> >
> > On Wed, Nov 20, 2013 at 11:38:42AM -0500, Dan Streetman wrote:
> >> The "compressor" and "enabled" params are currently hidden,
> >> this changes them to read-only, so userspace can tell if
> >> zswap is enabled or not and see what compressor is in use.
> >
> > Could you elaborate more why this pice of information is necessary for
> > userspace?
>
> For anyone interested in zswap, it's handy to be able to tell if it's
> enabled or not ;-) Technically people can check to see if the zswap
> debug files are in /sys/kernel/debug/zswap, but I think the actual
> "enabled" param is more obvious. And the compressor param is really
> the only way anyone from userspace can see what compressor's being
> used; that's helpful to know for anyone that might want to be using a
> non-default compressor.
So, it is needed for user not userspace? I tend to think that users are smart
enough to check cmdline for that.
AFAICS module_param exist here to provide simplest ability to handle the
setting via cmdline. zsawap is not able to be loaded as a module for now. If
it could, than there was reason to check which params were used while module
loading and guess how they affected zswap state.
>
> And of course, eventually we'll want to make the params writable, so
> the compressor can be changed dynamically, and zswap can be enabled or
> disabled dynamically (or at least enabled after boot).
module_params is not the best place to handle this, because they do not
provide any hooks for handling write unless I missed something. However,
making zswap state dynamically adjustable require not only setting the
numbers, but handling the correctness switching from one state to another.
Vladimir
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WARNING: multiple messages have this Message-ID (diff)
From: Vladimir Murzin <murzin.v@gmail.com>
To: Dan Streetman <ddstreet@ieee.org>
Cc: linux-mm@kvack.org, Seth Jennings <sjennings@variantweb.net>,
linux-kernel <linux-kernel@vger.kernel.org>,
Bob Liu <bob.liu@oracle.com>, Minchan Kim <minchan@kernel.org>,
Weijie Yang <weijie.yang@samsung.com>
Subject: Re: [PATCH] mm/zswap: change params from hidden to ro
Date: Fri, 22 Nov 2013 08:38:54 +0100 [thread overview]
Message-ID: <20131122073851.GB1853@hp530> (raw)
In-Reply-To: <CALZtONA81=R4abFMpMMtDZKQe0s-8+JxvEfZO3NEZ910VwRDmw@mail.gmail.com>
On Wed, Nov 20, 2013 at 12:52:47PM -0500, Dan Streetman wrote: > On Wed, Nov
20, 2013 at 12:33 PM, Vladimir Murzin <murzin.v@gmail.com> wrote: > > Hi Dan!
> >
> > On Wed, Nov 20, 2013 at 11:38:42AM -0500, Dan Streetman wrote:
> >> The "compressor" and "enabled" params are currently hidden,
> >> this changes them to read-only, so userspace can tell if
> >> zswap is enabled or not and see what compressor is in use.
> >
> > Could you elaborate more why this pice of information is necessary for
> > userspace?
>
> For anyone interested in zswap, it's handy to be able to tell if it's
> enabled or not ;-) Technically people can check to see if the zswap
> debug files are in /sys/kernel/debug/zswap, but I think the actual
> "enabled" param is more obvious. And the compressor param is really
> the only way anyone from userspace can see what compressor's being
> used; that's helpful to know for anyone that might want to be using a
> non-default compressor.
So, it is needed for user not userspace? I tend to think that users are smart
enough to check cmdline for that.
AFAICS module_param exist here to provide simplest ability to handle the
setting via cmdline. zsawap is not able to be loaded as a module for now. If
it could, than there was reason to check which params were used while module
loading and guess how they affected zswap state.
>
> And of course, eventually we'll want to make the params writable, so
> the compressor can be changed dynamically, and zswap can be enabled or
> disabled dynamically (or at least enabled after boot).
module_params is not the best place to handle this, because they do not
provide any hooks for handling write unless I missed something. However,
making zswap state dynamically adjustable require not only setting the
numbers, but handling the correctness switching from one state to another.
Vladimir
next prev parent reply other threads:[~2013-11-22 7:39 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-20 16:38 [PATCH] mm/zswap: change params from hidden to ro Dan Streetman
2013-11-20 16:38 ` Dan Streetman
2013-11-20 17:33 ` Vladimir Murzin
2013-11-20 17:33 ` Vladimir Murzin
2013-11-20 17:52 ` Dan Streetman
2013-11-20 17:52 ` Dan Streetman
2013-11-21 3:12 ` Weijie Yang
2013-11-21 3:12 ` Weijie Yang
2013-11-21 22:36 ` Dan Streetman
2013-11-21 22:36 ` Dan Streetman
2013-11-22 7:38 ` Vladimir Murzin [this message]
2013-11-22 7:38 ` Vladimir Murzin
2013-11-22 17:18 ` Dan Streetman
2013-11-22 17:18 ` Dan Streetman
2013-11-24 14:15 ` Vladimir Murzin
2013-11-24 14:15 ` Vladimir Murzin
2013-11-22 17:21 ` Seth Jennings
2013-11-22 17:21 ` Seth Jennings
2013-12-13 20:56 ` Dan Streetman
2013-12-13 20:56 ` Dan Streetman
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