Messages in this thread | | | Date | Thu, 03 Apr 2014 21:02:21 +0200 | From | Manfred Spraul <> | Subject | Re: [PATCH] ipc,shm: disable shmmax and shmall by default |
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Hi Davidlohr,
On 04/03/2014 02:20 AM, Davidlohr Bueso wrote: > The default size for shmmax is, and always has been, 32Mb. > Today, in the XXI century, it seems that this value is rather small, > making users have to increase it via sysctl, which can cause > unnecessary work and userspace application workarounds[1]. > > Instead of choosing yet another arbitrary value, larger than 32Mb, > this patch disables the use of both shmmax and shmall by default, > allowing users to create segments of unlimited sizes. Users and > applications that already explicitly set these values through sysctl > are left untouched, and thus does not change any of the behavior. > > So a value of 0 bytes or pages, for shmmax and shmall, respectively, > implies unlimited memory, as opposed to disabling sysv shared memory. > This is safe as 0 cannot possibly be used previously as SHMMIN is > hardcoded to 1 and cannot be modified. Are we sure that no user space apps uses shmctl(IPC_INFO) and prints a pretty error message if shmall is too small? We would break these apps.
-- Manfred
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