profiling levels：
0,关闭profile；1，只抓取slow查询；2，抓取所有数据。
启动profile并且设置Profile级别：
可以通过mongo shell启动，也可以通过驱动中的profile命令启动，启动后记录会被保存在system.profile collection下，可以使用db.setProfilingLevel来启动。默认slow为100 毫秒。db.setProfilingLevel可以有2个参数，第一个参数指定Profiling 级别，第二个参 数指定slow阀值。
检查当前Profiling 级别：可以通过db.getProfilingStatus()获取当前profiling级别，slowms 标记慢查询阀值。
关闭Profiling：还是使用db.setProfilingLevel(0)来关闭profiling
整个实例开启Profiling：mongod --prifile=1 --slowms=15
shard的Profiling：对shard的profiling要对每一个实例进行profiling
查看Profiling数据
可以直接在system.profile的collection上查看如：db.systen.profile.find()。或者使用show profile，会显示最近至少1ms时间运行的前5条记录。
Profiler概述
要修改system.profile collection的大小必须：1.关闭profiling，2.删除system.profile，3.然后重新创建system.profile，4.重启profile。
shell如下:db.setProfilingLevel(0)
,db.system.profile.drop()
,db.createCollect("system.profile",{cappedLtrue,size:4000000})
,db.setProfilingLevel(1)
query - # of queries per second
update - # of updates per second
delete - # of deletes per second
getmore - # of get mores (cursor batch) per second
command - # of commands per second, on a slave its local|replicated
flushes - # of fsync flushes per second
mapped - amount of data mmaped (total data size) megabytes
vsize - virtual size of process in megabytes
res - resident size of process in megabytes
faults - # of pages faults per sec
locked - name of and percent time for most locked database
idx miss - percent of btree page misses (sampled)
qr|qw - queue lengths for clients waiting (read|write)
ar|aw - active clients (read|write)
netIn - network traffic in - bits
netOut - network traffic out - bits
conn - number of open connections
set - replica set name
repl - replication type
PRI - primary (master)
SEC - secondary
REC - recovering
UNK - unknown
SLV - slave
RTR - mongos process ("router")
ub1405.system.users 0ms 0ms 0ms
ub1405.system.profile 0ms 0ms 0ms
b1405.system.namespaces 0ms 0ms 0ms
ub1405.system.indexes 0ms 0ms 0ms
ub1405.WapRecommend 0ms 0ms 0ms
ub1405.VisitPageInfo 0ms 0ms 0ms
ub1405.UsageInfo 0ms 0ms 0ms
ub1405.UpgradeInfo 0ms 0ms 0ms
ub1405.Switch 0ms 0ms 0ms
4.mongoperf
"db" : "ub1405",
"collections" : 17,
"objects" : 9939344,
"avgObjSize" : 336.2453477815035,
"dataSize" : 3342058180,
"storageSize" : 4501643264,
"numExtents" : 111,
"indexes" : 15,
"indexSize" : 322633136,
"fileSize" : 8519680000,
"nsSizeMB" : 16,
"dataFileVersion" : {
"major" : 4,
"minor" : 5
},
"ok" : 1
}
"ns" : "ub1405.WapRecommend",
"count" : 514,
"size" : 174416,
"avgObjSize" : 339.3307392996109,
"storageSize" : 430080,
"numExtents" : 3,
"nindexes" : 1,
"lastExtentSize" : 327680,
"paddingFactor" : 1,
"systemFlags" : 1,
"userFlags" : 0,
"totalIndexSize" : 24528,
"indexSizes" : {
"_id_" : 24528
},
"ok" : 1
}