[20170927]关于hugepages.txt

--//今天测试hugepages与内核参数nr_overcommit_hugepages,才发现HugePages_Surp表示什么?

--// [20170209]理解pre_page_sga参数.txt  => http://blog.itpub.net/267265/viewspace-2145481/ --// 0927hugepages与nr_overcommit_hugepages =>http://blog.itpub.net/267265/viewspace-2145481/

--//里面提到: $ cat /proc/meminfo | grep -i page AnonPages:        173732 kB PageTables:        11052 kB AnonHugePages:     38912 kB HugePages_Total:     600 HugePages_Free:      393 HugePages_Rsvd:       98 HugePages_Surp:        0 Hugepagesize:       2048 kB

--//alert内存如下: ************************ Large Pages Information ******************* Per process system memlock (soft) limit = 51 GB Total Shared Global Region in Large Pages = 610 MB (100%) Large Pages used by this instance: 305 (610 MB) Large Pages unused system wide = 295 (590 MB) Large Pages configured system wide = 600 (1200 MB) Large Page size = 2048 KB ********************************************************************

--实际上现在使用600-393=207. --HugePages_Rsvd:       98 --207+98=305 正好对上. 换一句化将现在还有98页面块没有使用.仅仅使用207块. --HugePages_Total-HugePages_Free+HugePages_Rsvd 就是 目前实例需要的页面数量.

--//注:这里看到的HugePages_Surp:        0.

--//而在如下链接测试中:http://blog.itpub.net/267265/viewspace-2145481/

--//修改/etc/sysctl.conf vm.nr_hugepages = 105 vm.nr_overcommit_hugepages=1000 --//启动数据库看到如下: Starting ORACLE instance (normal) Specified value of sga_max_size is too small, bumping to 637534208 ************************ Large Pages Information ******************* Parameter use_large_pages = ONLY Per process system memlock (soft) limit = 51 GB

Total Shared Global Region in Large Pages = 610 MB (100%)

Large Pages used by this instance: 305 (610 MB) Large Pages unused system wide = 0 (0 KB) Large Pages configured system wide = 305 (610 MB) Large Page size = 2048 KB ********************************************************************

# cat /proc/meminfo | grep -i hugepage AnonHugePages:         0 kB HugePages_Total:     305 HugePages_Free:       97 HugePages_Rsvd:       97 HugePages_Surp:      200 Hugepagesize:       2048 kB

--//我配置vm.nr_hugepages = 105,也就是还需要借用200.才能达到305. 这个就是HugePages_Surp的意思. --//我查了一下字典,估计surp是surpass的缩写,表示超越, 胜过的意思.

--//更正一下:应该是 surplus 过剩, 剩余, 留余额, 公积金

--//我这样设置HugePages_Free=HugePages_Rsvd. HugePages_Free:       97 HugePages_Rsvd:       97