[20191129]关于hugepages的问题.txt

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[20191129]关于hugepages的问题.txt --//这几天,论坛上有讨论hugepage的使用问题,链接: http://www.itpub.net/thread-2121953-1-1.html=>redhat5.8中没有HugePages http://www.itpub.net/thread-2121961-1-1.html=>LINUX是不是某些版本不支持大页内存功能 --//第一个对方使用XEN版本内核,更换应该没有问题. --//突然想起是否我设置vm.nr_hugepages = 0,而vm.nr_overcommit_hugepages = 1000是否可以启动. --//测试看看: 1.环境: # grep "^vm.nr" /etc/sysctl.conf vm.nr_hugepages = 0 vm.nr_overcommit_hugepages = 1000 SYS@book> @ ver1 PORT_STRING VERSION BANNER ------------------- ---------- ---------------------------------------------------------------------------- x86_64/Linux 2.4.xx 11.2.0.4.0 Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production SYS@book> show parameter use_large_pages NAME TYPE VALUE --------------- ------- ----- use_large_pages string ONLY # cat /etc/security/limits.conf oracle soft nproc 4095 oracle hard nproc 16384 oracle soft nofile 1024 oracle hard nofile 65536 * soft memlock 53248000 * hard memlock 53248000 # sysctl -p .. # grep -i page /proc/meminfo AnonPages: 90672 kB PageTables: 5956 kB AnonHugePages: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB 2.测试: SYS@book> startup ORACLE instance started. Total System Global Area 643084288 bytes Fixed Size 2255872 bytes Variable Size 205521920 bytes Database Buffers 427819008 bytes Redo Buffers 7487488 bytes Database mounted. Database opened. --//alert*.log记录如下: Fri Nov 29 10:10:47 2019 Adjusting the default value of parameter parallel_max_servers from 480 to 170 due to the value of parameter processes (200) Starting ORACLE instance (normal) ************************ Large Pages Information ******************* Parameter use_large_pages = ONLY Per process system memlock (soft) limit = 51 GB Total Shared Global Region in Large Pages = 618 MB (100%) Large Pages used by this instance: 309 (618 MB) Large Pages unused system wide = 0 (0 KB) Large Pages configured system wide = 309 (618 MB) Large Page size = 2048 KB ******************************************************************** # grep -i page /proc/meminfo AnonPages: 174548 kB PageTables: 14372 kB AnonHugePages: 0 kB HugePages_Total: 309 HugePages_Free: 72 HugePages_Rsvd: 72 HugePages_Surp: 309 Hugepagesize: 2048 kB --//OK没有问题. --//这样主要可能是内存碎片,可能一下子申请不到这么大的内存,我的测试环境需要很少的内存. --//也就是这样也可以启动数据库.这样好处关闭数据库内存全部回收. # free -m total used free shared buffers cached Mem: 129161 62561 66600 0 1538 56810 -/+ buffers/cache: 4212 124949 Swap: 30718 0 30718 SYS@book> shutdown immediate ; Database closed. Database dismounted. ORACLE instance shut down. # free -m total used free shared buffers cached Mem: 129161 61851 67309 0 1538 56809 -/+ buffers/cache: 3503 125657 Swap: 30718 0 30718 --//回收了67309-66600=709M. # grep -i page /proc/meminfo AnonPages: 88944 kB PageTables: 5912 kB AnonHugePages: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB 3.总结: 我个人认为使用hugepages是大势所趋,应该作为安装oracle的一个步骤,目前的机器配置内存都很高. 即使是很少的连接,消耗页面表也很大. # ipcs -m ------ Shared Memory Segments -------- key shmid owner perms bytes nattch status 0x00000000 32768 grid 640 4096 0 0x00000000 65537 grid 640 4096 0 0xed304ac0 98306 grid 640 4096 0 0x00000000 1081347 oracle 640 134217728 429 0x00000000 1114116 oracle 640 20132659200 429 0x5145def4 1146885 oracle 640 2097152 429 --//页面表占3694648KB,3694648/1024/1024 = 3.52G. --//3694648/429 = 8612.23 KB # grep -i page /proc/meminfo AnonPages: 6703096 kB PageTables: 3694648 kB AnonHugePages: 3147776 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB --//其后台进程的通过smem查询发现.USS占用会越来越大. # smem -tk -U oracle -P "ora_.*_xxxxx1" PID User Command Swap USS PSS RSS 21521 oracle ora_vktm_xxxxx1 0 2.2M 2.2M 17.4M 21533 oracle ora_acms_xxxxx1 0 2.2M 2.3M 17.5M 21477 oracle ora_psp0_xxxxx1 0 2.2M 2.3M 18.8M 6842 oracle ora_smco_xxxxx1 0 2.2M 2.4M 20.5M 3536 oracle ora_o003_xxxxx1 0 2.4M 2.5M 21.8M 23477 oracle ora_o001_xxxxx1 0 2.4M 2.6M 22.2M 24160 oracle ora_o002_xxxxx1 0 2.4M 2.6M 22.2M 22075 oracle ora_o000_xxxxx1 0 2.4M 2.6M 22.2M 21555 oracle ora_lmhb_xxxxx1 0 2.6M 2.8M 20.1M 21585 oracle ora_d000_xxxxx1 0 3.0M 3.1M 17.4M 24243 oracle ora_rcbg_xxxxx1 0 2.6M 3.1M 24.9M 21589 oracle ora_s000_xxxxx1 0 3.3M 3.4M 17.6M 21573 oracle ora_reco_xxxxx1 0 3.3M 3.6M 29.3M 21531 oracle ora_ping_xxxxx1 0 3.5M 3.7M 19.5M 24249 oracle ora_qmnc_xxxxx1 0 3.7M 3.8M 22.2M 21553 oracle ora_rms0_xxxxx1 0 3.9M 4.2M 30.7M 13231 oracle ora_w000_xxxxx1 0 3.8M 4.2M 26.8M 21575 oracle ora_rbal_xxxxx1 0 4.0M 4.2M 22.6M 24744 oracle ora_q000_xxxxx1 0 5.1M 5.4M 28.5M 7406 oracle ora_pz98_xxxxx1 0 2.5M 5.8M 81.4M 24241 oracle ora_gtx0_xxxxx1 0 3.4M 6.6M 44.9M 21525 oracle ora_gen0_xxxxx1 0 3.0M 6.6M 63.5M 21475 oracle ora_pmon_xxxxx1 0 4.9M 7.4M 47.6M 23675 oracle ora_arc2_xxxxx1 0 7.2M 7.6M 31.5M 22038 oracle ora_rsmn_xxxxx1 0 7.6M 7.7M 23.4M 28721 oracle ora_q002_xxxxx1 0 6.6M 9.2M 64.7M 21587 oracle ora_mark_xxxxx1 0 11.0M 11.1M 26.4M 21529 oracle ora_dbrm_xxxxx1 0 6.4M 12.3M 106.7M 21577 oracle ora_asmb_xxxxx1 0 4.0M 12.4M 178.1M 21527 oracle ora_diag_xxxxx1 0 10.1M 13.0M 39.4M 21567 oracle ora_lgwr_xxxxx1 0 6.9M 14.9M 78.1M 6972 oracle ora_nsa2_xxxxx1 0 21.6M 27.6M 84.2M 21539 oracle ora_lmd0_xxxxx1 0 18.3M 33.1M 187.4M 23673 oracle ora_arc1_xxxxx1 0 37.0M 37.7M 67.1M 21569 oracle ora_ckpt_xxxxx1 0 5.8M 39.6M 740.9M 24158 oracle ora_nsa3_xxxxx1 0 30.6M 41.0M 140.1M 21535 oracle ora_dia0_xxxxx1 0 35.0M 41.5M 97.0M 21583 oracle ora_mmnl_xxxxx1 0 11.2M 56.8M 193.6M 23417 oracle ora_arc0_xxxxx1 0 57.1M 59.5M 113.1M 23679 oracle ora_arc3_xxxxx1 0 57.7M 59.9M 111.2M 22036 oracle ora_lck0_xxxxx1 0 10.8M 61.8M 840.0M 21537 oracle ora_lmon_xxxxx1 0 13.0M 78.4M 409.9M 24316 oracle ora_cjq0_xxxxx1 0 12.3M 107.8M 1.1G 23217 oracle ora_pz99_xxxxx1 0 10.4M 162.9M 898.5M 21579 oracle ora_mmon_xxxxx1 0 29.4M 255.1M 2.0G 21571 oracle ora_smon_xxxxx1 0 14.0M 281.9M 2.2G 21557 oracle ora_mman_xxxxx1 0 348.1M 687.7M 2.5G 21561 oracle ora_dbw1_xxxxx1 0 120.5M 1.0G 4.9G 21559 oracle ora_dbw0_xxxxx1 0 117.0M 1.1G 5.2G 21563 oracle ora_dbw2_xxxxx1 0 119.7M 1.1G 5.2G 21565 oracle ora_dbw3_xxxxx1 0 135.5M 1.1G 5.2G 21545 oracle ora_lms1_xxxxx1 0 755.5M 2.0G 6.9G 21541 oracle ora_lms0_xxxxx1 0 764.7M 2.1G 7.0G 21549 oracle ora_lms2_xxxxx1 0 791.2M 2.2G 7.4G ------------------------------------------------------------------------------- 54 1 0 3.6G 12.6G 54.4G --//而使用hugepages根本看不到这样的情况.