[20170927]關于hugepages.txt

--//今天測試hugepages與內核參數nr_overcommit_hugepages,才發現HugePages_Surp表示什么?

--// [20170209]理解pre_page_sga參數.txt? => http://blog.itpub.net/267265/viewspace-2145481/
--// 0927hugepages與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內存如下:
************************ 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
********************************************************************

--實際上現在使用600-393=207.
--HugePages_Rsvd:?????? 98
--207+98=305 正好對上. 換一句化將現在還有98頁面塊沒有使用.僅僅使用207塊.
--HugePages_Total-HugePages_Free+HugePages_Rsvd 就是 目前實例需要的頁面數量.

--//注:這里看到的HugePages_Surp:??????? 0.

--//而在如下鏈接測試中:http://blog.itpub.net/267265/viewspace-2145481/

--//修改/etc/sysctl.conf
vm.nr_hugepages = 105
vm.nr_overcommit_hugepages=1000
--//啟動數據庫看到如下:
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,也就是還需要借用200.才能達到305. 這個就是HugePages_Surp的意思.
--//我查了一下字典,估計surp是surpass的縮寫,表示超越, 勝過的意思.

--//我這樣設置HugePages_Free=HugePages_Rsvd.
HugePages_Free:?????? 97
HugePages_Rsvd:?????? 97

轉載于:https://www.cnblogs.com/lfree/p/7600365.html

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