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items: [RFC][PATCH v2 1/7] Scaling msgmni to the amount of lowmem

[RFC][PATCH v2 1/7] Scaling msgmni to the amount of lowmem
type: item
description: [PATCH 01/07] This patch computes msg_ctlmni to make it scale with the amount of lowmem. msg_ctlmni is now set to make the message queues occupy 1/32 of the available lowmem. Some cleaning has also been done for the MSGPOOL constant: the msgctl man page says it's not used, but it also defines it as a size in bytes (the code expresses it in Kbytes). Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net> --- include/linux/msg.h | 14 ++++++++++++-- ipc/msg.c | 37 ++++++++++++++++++++++++++++++++++++- 2 files changed, 48 insertions(+), 3 deletions(-) Index: linux-2.6.24/include/linux/msg.h =================================================================== --- linux-2.6.24.orig/include/linux/msg.h 2008-01-29 16:54:40.000000000 +0100 +++ linux-2.6.24/include/linux/msg.h 2008-01-31 08:47:48.000000000 +0100 @@ -49,16 +49,26 @@ struct msginfo { unsigned short msgseg; }; +/* + * Scaling factor to compute msgmni: + * the memory dedicated to msg queues (msgmni * msgmnb) should occupy + * at most 1/MSG_MEM_SCALE of the lowmem (see the formula in ipc/msg.c): + * up to 8MB : msgmni = 16 (MSGMNI) + * 4 GB : msgmni = 8K + * more than 16 GB : msgmni = 32K (IPCMNI) + */ +#define MSG_MEM_SCALE 32 + #define MSGMNI 16 /* <= IPCMNI */ /* max # of msg queue identifiers */ #define MSGMAX 8192 /* <= INT_MAX */ /* max size of message (bytes) */ #define MSGMNB 16384 /* <= INT_MAX */ /* default max size of a message queue */ /* unused */ -#define MSGPOOL (MSGMNI*MSGMNB/1024) /* size in kilobytes of message pool */ +#define MSGPOOL (MSGMNI * MSGMNB) /* size in bytes of message pool */ #define MSGTQL MSGMNB /* number of system message headers */ #define MSGMAP MSGMNB /* number of entries in message map */ #define MSGSSZ 16 /* message segment size */ -#define __MSGSEG ((MSGPOOL*1024)/ MSGSSZ) /* max no. of segments */ +#define __MSGSEG (MSGPOOL / MSGSSZ) /* max no. of segments */ #define MSGSEG (__MSGSEG <= 0xffff ? __MSGSEG : 0xffff) #ifdef __KERNEL__ Index: linux-2.6.24/ipc/msg.c =================…
creator: Nadia Derbey
date: 2008-01-31T13:40:19-00:00