shmall, shmmax, shmmni & swap
Hello all, I need help in configuring shared memory on Linux 6.3 and LInux 7.2. What is shmall ? This kernelparameter does not exist on Solaris nor HP. Why is shmmni not existing ? I was able to increase shmmax (echo 134217728 > /proc/sys/kernel/shmmax) and new value was visible; however, my Versant database server could not allocate more shared memory. I also tried to increase shmall as root, but value was not saved in /proc/sys/kernel/shmall. Any advise on how to increase shared memory is more then welcome. Thanks Katharina
Katharina Kampf wrote:
Hello all,
I need help in configuring shared memory on Linux 6.3 and LInux 7.2. What is shmall ?
[from man 2 shmget] SHMALL: System wide maximum of shared memory pages:policy dependent. SHMMNI: System wide maximum number of shared memory segments: implementation dependent (currently 4096). SHMMAX: Maximum size in bytes for a shared memory seg ment: implementation dependent (currently 4M). [from Documentation/sysctl/kernel.txt] (running kernel 2.2.16) 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.
This kernelparameter does not exist on Solaris nor HP. Why is shmmni not existing ?
SHMALL,SHMMNI,SHMMAX are no kernel paramters. They define limits affecting the results of systemcalls like shmget(),shmat() or shmdt() The presence of these defines depend on a kernel build with SystemV IPC support. For a linux kernel the configuration file should then contain a 'CONFIG_SYSVIPC=y' (??!!)
I was able to increase shmmax (echo 134217728 > /proc/sys/kernel/shmmax) and new value was visible; however, my Versant database server could not allocate more shared memory.
? could or did not ? Any error messages? - [from linux/asm-i386/shmparam.h:] #define SHMMAX 0x2000000 /* max shared seg size (bytes) */ /* Try not to change the default shipped SHMMAX - people rely on it */
I also tried to increase shmall as root, but value was not saved in /proc/sys/kernel/shmall.
Any advise on how to increase shared memory is more then welcome.
Thanks Katharina
Daniel
participants (2)
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D. Wolpert
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Katharina Kampf