From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>,
Seth Jennings <sjenning@linux.vnet.ibm.com>,
Konrad Rzeszutek Wilk <konrad@darnok.org>,
Minchan Kim <minchan@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Bob Liu <bob.liu@oracle.com>
Subject: Re: [PATCH 02/10] staging: zcache: remove zcache_freeze
Date: Thu, 11 Apr 2013 13:05:18 -0700 [thread overview]
Message-ID: <20130411200518.GA5268@kroah.com> (raw)
In-Reply-To: <ecb7519b-669a-48e4-b217-a77ecb60afd4@default>
On Thu, Apr 11, 2013 at 10:13:42AM -0700, Dan Magenheimer wrote:
> > From: Wanpeng Li [mailto:liwanp@linux.vnet.ibm.com]
> > Subject: [PATCH 02/10] staging: zcache: remove zcache_freeze
> >
> > The default value of zcache_freeze is false and it won't be modified by
> > other codes. Remove zcache_freeze since no routine can disable zcache
> > during system running.
> >
> > Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
>
> I'd prefer to leave this code in place as it may be very useful
> if/when zcache becomes more tightly integrated into the MM subsystem
> and the rest of the kernel. And the subtleties for temporarily disabling
> zcache (which is what zcache_freeze does) are non-obvious and
> may cause data loss so if someone wants to add this functionality
> back in later and don't have this piece of code, it may take
> a lot of pain to get it working.
>
> Usage example: All CPUs are fully saturated so it is questionable
> whether spending CPU cycles for compression is wise. Kernel
> could disable zcache using zcache_freeze. (Yes, a new entry point
> would need to be added to enable/disable zcache_freeze.)
>
> My two cents... others are welcome to override.
I will not override, and did not take this patch.
greg k-h
next prev parent reply other threads:[~2013-04-11 20:05 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <<1365553560-32258-1-git-send-email-liwanp@linux.vnet.ibm.com>
[not found] ` <<1365553560-32258-3-git-send-email-liwanp@linux.vnet.ibm.com>
2013-04-11 17:13 ` [PATCH 02/10] staging: zcache: remove zcache_freeze Dan Magenheimer
2013-04-11 20:05 ` Greg Kroah-Hartman [this message]
2013-04-11 17:17 ` [PATCH 00/10] staging: zcache/ramster: fix and ramster/debugfs improvement Dan Magenheimer
2013-04-10 0:25 Wanpeng Li
2013-04-10 0:25 ` [PATCH 01/10] staging: zcache: fix account foregin counters against zero-filled pages Wanpeng Li
2013-04-10 0:25 ` [PATCH 02/10] staging: zcache: remove zcache_freeze Wanpeng Li
2013-04-10 0:25 ` [PATCH 03/10] staging: ramster: Provide accessory functions for counter increase Wanpeng Li
2013-04-10 0:25 ` [PATCH 04/10] staging: ramster: Provide accessory functions for counter decrease Wanpeng Li
2013-04-10 0:25 ` [PATCH 05/10] staging: ramster: Move debugfs code out of ramster.c file Wanpeng Li
2013-04-11 20:04 ` Greg Kroah-Hartman
2013-04-10 0:25 ` [PATCH 06/10] staging: ramster/debug: Use an array to initialize/use debugfs attributes Wanpeng Li
2013-04-10 0:25 ` [PATCH 07/10] staging: ramster/debug: Add RAMSTER_DEBUG Kconfig entry Wanpeng Li
2013-04-10 0:25 ` [PATCH 08/10] staging: ramster: Add incremental accessory counters Wanpeng Li
2013-04-10 0:25 ` [PATCH 09/10] staging: zcache/debug: fix coding style Wanpeng Li
2013-04-10 0:26 ` [PATCH 10/10] staging: ramster: add how-to for ramster Wanpeng Li
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