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From: "John Stoffel" <john@stoffel.org>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>,
	Michal@stoffel.org, eric.dumazet@gmail.com, mst@redhat.com,
	netdev@vger.kernel.org, jasowang@redhat.com,
	Randy Dunlap <rdunlap@infradead.org>,
	linux-kernel@vger.kernel.org,
	Matthew Wilcox <willy@infradead.org>, Hocko <mhocko@kernel.org>,
	linux-mm@kvack.org, dm-devel@redhat.com,
	Vlastimil Babka <vbabka@suse.cz>,
	Andrew@stoffel.org, David Rientjes <rientjes@google.com>,
	Morton <akpm@linux-foundation.org>,
	virtualization@lists.linux-foundation.org,
	David Miller <davem@davemloft.net>,
	edumazet@google.com
Subject: Re: [dm-devel] [PATCH v5] fault-injection: introduce kvmalloc fallback options
Date: Thu, 26 Apr 2018 14:58:28 -0400	[thread overview]
Message-ID: <23266.8532.619051.784274@quad.stoffel.home> (raw)
In-Reply-To: <1524697697.4100.23.camel@HansenPartnership.com>

>>>>> "James" == James Bottomley <James.Bottomley@HansenPartnership.com> writes:

James> On Wed, 2018-04-25 at 19:00 -0400, Mikulas Patocka wrote:
>> 
>> On Wed, 25 Apr 2018, James Bottomley wrote:
>> 
>> > > > Do we really need the new config option?  This could just be
>> > > > manually  tunable via fault injection IIUC.
>> > > 
>> > > We do, because we want to enable it in RHEL and Fedora debugging
>> > > kernels, so that it will be tested by the users.
>> > > 
>> > > The users won't use some extra magic kernel options or debugfs
>> files.
>> > 
>> > If it can be enabled via a tunable, then the distro can turn it on
>> > without the user having to do anything.  If you want to present the
>> > user with a different boot option, you can (just have the tunable
>> set
>> > on the command line), but being tunable driven means that you don't
>> > have to choose that option, you could automatically enable it under
>> a
>> > range of circumstances.  I think most sane distributions would want
>> > that flexibility.
>> > 
>> > Kconfig proliferation, conversely, is a bit of a nightmare from
>> both
>> > the user and the tester's point of view, so we're trying to avoid
>> it
>> > unless absolutely necessary.
>> > 
>> > James
>> 
>> BTW. even developers who compile their own kernel should have this
>> enabled by a CONFIG option - because if the developer sees the option
>> when browsing through menuconfig, he may enable it. If he doesn't see
>> the option, he won't even know that such an option exists.

James> I may be an atypical developer but I'd rather have a root canal
James> than browse through menuconfig options.  The way to get people
James> to learn about new debugging options is to blog about it (or
James> write an lwn.net article) which google will find the next time
James> I ask it how I debug XXX.  Google (probably as a service to
James> humanity) rarely turns up Kconfig options in response to a
James> query.

I agree with James here.  Looking at the SLAB vs SLUB Kconfig entries
tells me *nothing* about why I should pick one or the other, as an
example.

John

  parent reply	other threads:[~2018-04-26 19:14 UTC|newest]

Thread overview: 110+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-18 14:34 [PATCH] net: don't use kvzalloc for DMA memory Mikulas Patocka
2018-04-18 16:05 ` Eric Dumazet
2018-04-18 16:44   ` Mikulas Patocka
2018-04-18 16:51     ` Eric Dumazet
2018-04-18 17:47       ` David Miller
2018-04-18 17:55         ` Mikulas Patocka
2018-04-18 18:00         ` Michael S. Tsirkin
2018-04-18 17:49       ` Mikulas Patocka
2018-04-18 17:46     ` David Miller
2018-04-18 17:53       ` Mikulas Patocka
2018-04-19 16:12         ` [PATCH] kvmalloc: always use vmalloc if CONFIG_DEBUG_VM Mikulas Patocka
2018-04-19 16:25           ` Eric Dumazet
2018-04-19 16:28             ` Mikulas Patocka
2018-04-19 16:43           ` Michael S. Tsirkin
2018-04-19 21:27             ` [PATCH] kvmalloc: always use vmalloc if CONFIG_DEBUG_SG Mikulas Patocka
2018-04-19 18:28           ` [PATCH] kvmalloc: always use vmalloc if CONFIG_DEBUG_VM Vlastimil Babka
2018-04-19 19:47           ` Andrew Morton
2018-04-19 21:19             ` Mikulas Patocka
2018-04-19 23:22               ` Andrew Morton
2018-04-20 12:16                 ` Mikulas Patocka
2018-04-20 11:47           ` Matthew Wilcox
2018-04-20 12:20             ` Mikulas Patocka
2018-04-23 15:25               ` Michael S. Tsirkin
2018-04-20 13:08           ` Michal Hocko
2018-04-20 13:41             ` Matthew Wilcox
2018-04-20 13:49               ` Michal Hocko
2018-04-20 20:56                 ` Mikulas Patocka
2018-04-20 20:54             ` Mikulas Patocka
2018-04-20 21:02               ` Matthew Wilcox
2018-04-20 21:21                 ` Mikulas Patocka
2018-04-21 14:47                   ` Matthew Wilcox
2018-04-22 13:03                     ` Michal Hocko
2018-04-23 14:24                       ` Mikulas Patocka
2018-04-23 15:10                         ` Michal Hocko
2018-04-23 23:20                           ` Mikulas Patocka
2018-04-23 14:06                     ` Mikulas Patocka
2018-04-23 15:15                       ` Michal Hocko
2018-04-24  0:06                         ` [PATCH v3] kvmalloc: always use vmalloc if CONFIG_DEBUG_SG Mikulas Patocka
2018-04-24  2:47                           ` David Rientjes
2018-04-24 11:04                             ` Mikulas Patocka
2018-04-24  3:46                           ` Matthew Wilcox
2018-04-24 12:29                             ` Mikulas Patocka
2018-04-24 17:16                               ` Matthew Wilcox
2018-04-24 18:41                                 ` Mikulas Patocka
2018-05-15  1:13                                   ` Joonsoo Kim
2018-04-24 12:51                           ` Michal Hocko
2018-04-24 15:50                             ` Mikulas Patocka
2018-04-24 16:29                               ` Michal Hocko
2018-04-24 17:00                                 ` Mikulas Patocka
2018-04-24 17:03                                   ` Michal Hocko
2018-04-24 17:28                                     ` Mikulas Patocka
2018-04-24 17:38                                       ` Michal Hocko
2018-04-25 20:02                                         ` [PATCH] fault-injection: reorder config entries Mikulas Patocka
2018-04-26  3:21                                           ` Randy Dunlap
2018-04-25 20:02                                         ` [PATCH v4] fault-injection: introduce kvmalloc fallback options Mikulas Patocka
2018-04-25 20:20                                           ` Randy Dunlap
2018-04-25 20:57                                             ` [PATCH v5] " Mikulas Patocka
2018-04-25 21:11                                               ` Randy Dunlap
2018-04-25 21:18                                               ` David Rientjes
2018-04-25 21:22                                                 ` Mikulas Patocka
2018-04-25 22:17                                                   ` [dm-devel] " James Bottomley
2018-04-25 22:42                                                     ` Mikulas Patocka
2018-04-25 22:49                                                       ` David Rientjes
2018-04-25 22:56                                                         ` Mikulas Patocka
2018-04-26 12:58                                                       ` Michal Hocko
2018-04-26 14:28                                                         ` Mikulas Patocka
2018-04-26 14:45                                                           ` James Bottomley
2018-04-26 15:05                                                             ` Mikulas Patocka
2018-04-26 15:24                                                               ` James Bottomley
2018-04-26 15:44                                                                 ` Mikulas Patocka
2018-04-26 15:59                                                                   ` Michael S. Tsirkin
2018-04-26 16:07                                                                     ` Mikulas Patocka
2018-04-26 18:49                                                                       ` Michael S. Tsirkin
2018-04-26 18:54                                                                         ` Mikulas Patocka
2018-04-26 19:14                                                                           ` Michael S. Tsirkin
2018-04-26 19:36                                                                             ` Mikulas Patocka
2018-04-26 19:45                                                                               ` Michael S. Tsirkin
2018-04-26 20:05                                                                                 ` Mikulas Patocka
2018-04-26 18:58                                                                     ` Mikulas Patocka
2018-04-26 19:05                                                                       ` Michael S. Tsirkin
2018-04-26 15:55                                                                 ` Mikulas Patocka
2018-04-25 23:00                                                     ` Mikulas Patocka
2018-04-25 23:08                                                       ` James Bottomley
2018-04-26 14:55                                                         ` Mikulas Patocka
2018-04-26 15:22                                                           ` Mikulas Patocka
2018-04-26 18:58                                                         ` John Stoffel [this message]
2018-04-26 21:50                                                           ` Mikulas Patocka
2018-04-26 22:21                                                             ` Michael S. Tsirkin
2018-04-26 22:52                                                               ` Mikulas Patocka
2018-04-27  8:25                                                                 ` Michal Hocko
2018-04-27 10:20                                                                   ` Mikulas Patocka
2018-04-27 23:20                                                               ` Mikulas Patocka
2018-04-30 18:27                                                             ` John Stoffel
2018-04-30 21:07                                                               ` Mikulas Patocka
2018-05-02 13:38                                                                 ` John Stoffel
2018-05-03 17:40                                                                   ` Mikulas Patocka
2018-04-24  0:25                         ` [PATCH] kvmalloc: always use vmalloc if CONFIG_DEBUG_VM Mikulas Patocka
2018-04-24 13:31                           ` Michal Hocko
2018-04-24 15:30                             ` Mikulas Patocka
2018-04-24 16:12                               ` Michal Hocko
2018-04-24 16:29                                 ` Michal Hocko
2018-04-24 16:33                                 ` Mikulas Patocka
2018-05-02  0:36                                   ` Andrew Morton
2018-05-02 13:33                                     ` Mike Snitzer
2018-05-02 13:40                                       ` [dm-devel] " John Stoffel
2018-05-03 17:32                                     ` [PATCH] " Mikulas Patocka
2018-04-18 17:45   ` [PATCH] net: don't use kvzalloc for DMA memory David Miller
2018-04-18 17:55   ` Michael S. Tsirkin
2018-04-18 20:38     ` Eric Dumazet
2018-04-19  4:00       ` Michael S. Tsirkin

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