From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Seth, Rohit" Date: Fri, 18 Oct 2002 16:24:55 +0000 Subject: RE: [Linux-ia64] Kernel Shared Memory Max (shmmax) Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org The restriction is coming out of default parameters set in Linux (file include/linux/shm.h). These values could be changed through /proc/sys/kernel/shm* interface. And if a site permanentlly wants to have higher values for this parameters then that can be achieved by something like rc.local Have not seen any distribution increasing the default values for IA-64 yet. rohit > -----Original Message----- > From: miyoshi@hpc.bs1.fc.nec.co.jp > [mailto:miyoshi@hpc.bs1.fc.nec.co.jp] > Sent: Thursday, October 17, 2002 6:07 PM > To: rohit.seth@intel.com; dcooper@atcc.necsys.com > Cc: ia64-list@redhat.com; linux-ia64@linuxia64.org; > jfredin@atcc.necsys.com > Subject: Re: [Linux-ia64] Kernel Shared Memory Max (shmmax) > > > > Hi, > > I suppose '8G' described below means default shmall, that is > 524288 * 16K. And I think there is no restrictions around 8G on IA-64. > > Regards, > > > > And based on that the total amount of shared memory > segment that can > > > be created in IA-64 platform (with 16K page size) is 8G. > > > > Does this still hold true in newer kernel releases (since > 03/2002)? > > Is 8G the > > max for IA64 kernel? > > > > Thanks, > > Donny > > > > On Thu March 14 2002 5:13 pm, Seth, Rohit wrote: > > > shmmax is the size of largest shared memory (in bytes) > segment that > > > the kernel allows. System wide value of total shared > memory value > > > is given by shmall parameter. Currently the default value for > > > shmmax is (extrememly > > > low) 32MB. And based on that the total amount of shared > memory segment > > > that can be created in IA-64 platform (with 16K page > size) is 8G. There is > > > no direct relationship between shmmax value and the > amount of physical > > > memory available in the system. Though you will never be > able to create a > > > shared memory segment bigger then the total memory (Free > RAM+Free SWAP) > > > available on the machine (unless you change the > sysctl_overcommit_memory). > > > Besides that, this low default value of 32MB just adds > overhead for big > > > memory systems. It will be nice to change this default > value to 2G at > > > least for IA-64 machines. > > > > > > You can also change this value of shm* (shmmax etc.) by writing > > > proper values in /proc/sys/kernel/shm* > > > > > > rohit > > > > > > -----Original Message----- > > > From: Donny Cooper [mailto:dcooper@atcc.necsys.com] > > > Sent: Thursday, March 14, 2002 2:40 PM > > > To: ia64-list@redhat.com; linux-ia64@linuxia64.org > > > Subject: [Linux-ia64] Kernel Shared Memory Max (shmmax) > > > > > > > > > > > > Does the maximum possible shared memory (shmmax) increase > with the > > > Enterprise kernel? > > > > > > Below is from doc/sysctl/kernel.txt document. > > > Is this document valid for IA-64 kernel? > > > > > > It seems you can set this value to pretty much anything > (even larger > > > than the available memory), so I'm assuming the value gets > > > intelligently truncated to the max supported. How can I > check how > > > much shared mem is available, `free` or `top` just shows what's > > > used, right? > > > > > > ...doc/sysctl/kernel.txt > > > =============================== > > > > > > shmmax: > > > > > > This value can be used to query and set the run time limit on the > > > maximum shared memory segment size that can be created. Shared > > > memory segments up to 1Gb are now supported in the kernel. This > > > value defaults to SHMMAX. > > > > > > =============================== > > > > > > > > > Thanks, > > > ----------------------------------- > > > Donny Cooper > > > NEC Systems, Inc. > > > Advanced Technical Computing Center > > > dcooper@atcc.necsys.com > > > ----------------------------------- > > > > > > > > > _______________________________________________ > > > Linux-IA64 mailing list > > > Linux-IA64@linuxia64.org > > > http://lists.linuxia64.org/lists/listinfo/linux-ia64 > > > > > > > > > > > > _______________________________________________ > > > ia64-list mailing list > > > ia64-list@redhat.com > > > > -- > > ================> > Donny Cooper > > NEC Solutions (America), Inc. > > Advanced Technical Computing Center > > ph: +1-281-465-1506 > > Donny.Cooper@NECsam.com > > ================> > > > > > > > _______________________________________________ > > ia64-list mailing list > > ia64-list@redhat.com > > https://listman.redhat.com/mailman/listinfo/ia64-list > > >