From: Waiman Long <longman@redhat.com>
To: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>,
Kees Cook <keescook@chromium.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jonathan Corbet <corbet@lwn.net>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-doc@vger.kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
Matthew Wilcox <willy@infradead.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Takashi Iwai <tiwai@suse.de>, Davidlohr Bueso <dbueso@suse.de>,
manfred@colorfullife.com
Subject: Re: [PATCH v8 3/5] ipc: Allow boot time extension of IPCMNI from 32k to 2M
Date: Fri, 17 Aug 2018 21:15:45 -0400 [thread overview]
Message-ID: <5ddb67bb-872b-c8c1-7838-2622195ae1fc@redhat.com> (raw)
In-Reply-To: <20180817164548.GA32382@linux-r8p5>
On 08/17/2018 12:45 PM, Davidlohr Bueso wrote:
> Cc'ing Manfred.
>
> On Mon, 18 Jun 2018, Waiman Long wrote:
>
>> The maximum number of unique System V IPC identifiers was limited to
>> 32k. That limit should be big enough for most use cases.
>>
>> However, there are some users out there requesting for more. To satisfy
>> the need of those users, a new boot time kernel option "ipcmni_extend"
>> is added to extend the IPCMNI value to 2M. This is a 64X increase which
>> hopefully is big enough for them.
>
> Could you please provide more info on the need of these users and how
> you came up with this new value (which just seems quite arbitrary)?
>
> Thanks,
> Davidlohr
Red Hat has a customer that is migrating from Solaris to Linux. Some of
their applications just happen to use more than 32k of shared memory
segments. I think Solaris allows up to 16M unique ID.
Yes, the amount of increase is a bit arbitrary. I was trying to balance
how many bits should be left for sequence number. Maybe I should just
take 8 more bits for ID and leave 8 bits for sequence number to match
Solaris.
-Longman
next prev parent reply other threads:[~2018-08-18 1:15 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-18 10:28 [PATCH v8 0/5] ipc: IPCMNI limit check for *mni & increase that limit Waiman Long
2018-06-18 10:28 ` [PATCH v8 1/5] ipc: IPCMNI limit check for msgmni and shmmni Waiman Long
2018-06-28 3:16 ` Luis R. Rodriguez
2018-08-17 16:51 ` Davidlohr Bueso
2018-06-18 10:28 ` [PATCH v8 2/5] ipc: IPCMNI limit check for semmni Waiman Long
2018-06-28 22:39 ` Luis R. Rodriguez
2018-06-29 7:26 ` Waiman Long
2018-08-17 16:53 ` Davidlohr Bueso
2018-06-18 10:28 ` [PATCH v8 3/5] ipc: Allow boot time extension of IPCMNI from 32k to 2M Waiman Long
2018-08-17 16:45 ` Davidlohr Bueso
2018-08-18 1:15 ` Waiman Long [this message]
2018-10-02 16:32 ` Manfred Spraul
2018-10-02 17:43 ` Waiman Long
2018-06-18 10:28 ` [PATCH v8 4/5] ipc: Conserve sequence numbers in extended IPCMNI mode Waiman Long
2018-06-18 10:28 ` [PATCH v8 5/5] ipc: Add a new ipcmni_compat sysctl to fall back to old behavior Waiman Long
2018-06-18 11:36 ` kbuild test robot
2018-06-18 14:27 ` kbuild test robot
2018-08-17 16:50 ` [PATCH v8 0/5] ipc: IPCMNI limit check for *mni & increase that limit Davidlohr Bueso
2018-09-06 22:24 ` Andrew Morton
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