关于swap

guoq.lee

我看到一篇文章，里面有很多不明白的地方。请问红色的公式各个数字代表什么？

I think the issue here is with understanding what the data from "swap -s" means.

Here's from one of my internal systems:

# swap -l
swapfile             dev  swaplo blocks   free
/dev/dsk/c0t1d0s1   32,9      16 8201840 8201840
/dev/md/dsk/d209    85,209     16 67108848 67108848
/dev/md/dsk/d210    85,210     16 67108848 67108848
/dev/md/dsk/d211    85,211     16 67108848 67108848
/dev/md/dsk/d212    85,212     16 67108848 67108848
/dev/md/dsk/d213    85,213     16 67108848 67108848

# sys
XXX   08/03/09   10:02:16   SunOS 5.10 Generic_139555-04   sun4u
2520/0 MHz   8 CPUs   32.00 GB memory   SUNW,SPARC-Enterprise

# swap -s
total: 71280k bytes allocated + 12368k reserved = 83648k used, 200001416k
available

So the 200001416k is equal to the 32 * 5 + 4 GB in actual swap files plus
32 GB in memory minus the kernel space (and whatever is in /tmp; I didn't
check).

When I start oracle here:

Total System Global Area 4932501504 bytes
Fixed Size                  2047312 bytes
Variable Size             620757680 bytes
Database Buffers         4294967296 bytes
Redo Buffers               14729216 bytes
Database mounted.
Database opened.

# pmap -xs 9020 | grep -i ism

0000000380000000 4816896 4816896 - 4816896 4M rwxsR [ ism shmid=0x1 ] 00000004A6000000 16 16 - 16 8K rwxsR [ ism shmid=0x1 ]

So it's using ISM.

bur834-98# swap -s

total: 5140592k bytes allocated + 33968k reserved = 5174560k used, 194842040k available

So now the available space is about 6G less, which is pretty much the total
of the ~5G SGA plus swap space for the oracle processes.

If I set "sga_max_size = 7159641169" and restart:

Total System Global Area 7163871232 bytes
Fixed Size                  2051616 bytes
Variable Size            2852131296 bytes
Database Buffers         4294967296 bytes
Redo Buffers               14721024 bytes
Database mounted.
Database opened.

# ps -ef | grep lgwr
  oracle 11586     1   0 10:10:47 ?           0:00 ora_lgwr_XXX

bur834-98# pmap -xs 11586 | grep -i dism

0000000380000000 16384 16384 - - 4M rwxs- [ dism shmid=0x3 ] 0000000381000000 2191360 12288 - - - rwxs- [ dism shmid=0x3 ]

...

So it's now using DISM instead.

# swap -s

total: 5144680k bytes allocated + 2212928k reserved = 7357608k used, 187819608k available

Now the total is reduced by an additional 7G to save space for the DISM backing.
Note the other memory use hasn't changed, so the size in memory remains the
same, about 5G.  There's just extra swap space allocated.

So things are working as expected; it's just the interpretation of the "swap -s"
that's causing problems.

Regards,

Dave Miller

谢谢