explicitly defined as null.
2048
Ansi_null_dflt_off
Change the session behavior to not use ANSI compatibility null. NULL values are not allowed for new columns that are not explicitly defined as null.
4096
Concat_null_yields_null
Returns NULL when concatenating null values with strings.
8192
Numeric_roundabort
An error is generated when the expression precision is reduced.
16384
Xact_abort
I
Implement an embedded operating system that can't do anything
1. First determine the CPU. Here we use embedded CPU for simplicity, such as the arm series. The reason why we use a short Instruction Set)The convenience of a type of CPU is that there is no distinction between the real mode and the protection mode, and linear unified addressing is adopted, that is, the segment is not requiredPage-based memory management, or the chip is integrated with so
# show ' Boot: ' PromptTimeout 60 # Wait timeout, unit 1/10 seconds, automatically start default specified label after timeoutDisplay Boot.msg # Displays the contents of boot.msg, the file path is relative to the root directory of the TFTP server (default/tftpboot), so the boot.msg file absolute path is in/tftpboot/boot.msg.F1 Boot.msg # Press the ' F1 ' key to display the fileF2 options.msgF3 general.msgF4 param.msgF5 rescue.msgLabel 1 # ' label ' specifies the keyword you entered at the ' Boo
Sysctl is an interface that allows you to change the Linux system you are running. It contains advanced options for TCP/IP stacks and virtual memory systems, which allows experienced administrators to improve compelling system performance. Sysctl can be read to set more than 500 system variables. Based on this, SYSCTL (8) offers two features: Read and modify system settings.first look at a well tuned sysctl.conf simple configuration that may apply to some friendssysctl.conf Configuration paramet
Implement a simple Embedded Operating System (1)
Implement an embedded operating system that can't do anything1. First determine the CPU. Here we use embedded CPU for simplicity, such as the arm series. The reason why we use a short Instruction Set)The convenience of a type of CPU is that there is no distinction between the real mode and the protection mode, and linear unified addressing is adopted, that is, the segment is not requiredPag
...... * % O ....0000110: 0000 0000 0000 0000 0000 0000 0000 ................All 0 s...20173f0: 0000 0000 0000 0000 0000 0000 0000 ................
We can see that the superblock format is small Based on the ext3_super_block structure and the English description,The first is u32, 205e 0000, that is, 5e20, decimal 24096, total inodeThe second is also u32, 6678 0100, that is, 17866, decimal 96358, the total number of blocksThe two numbers match dumpe2fs/dev/sda1.
5.Copy backupThe backup of super
[0x1ebd0000, 0x227d0000, 0x227d0000)Eden space 49152 K, 99% used[0x1ebd0000, 0x21bce430, 0x21bd0000)From space 6144 K, 55% used[0x221d0000, 0x22527e10, 0x227d0000)To space 6144 K, 0% used [0x21bd0000, 0x21bd0000, 0x221d0000)Tenured generation total 69632 K, used 2696 K [0x227d0000, 0x26bd0000, 0x26bd0000)The space 69632 K, 3% used[0x227d0000, 0x22a720f8, 0x22a72200, 0x26bd0000)Compacting perm Gen total 8192 K, used 2898 K [0x26bd0000, 0x273d0000, 0x2
(all machines) and resource class.
Type: resourcetype_disk (File resource), resource usage: resourceusage_container (all container resources ),
The network level is the highest level (nil). In this way, you can obtain a handle to further list network resources. The specific procedure section is as follows:
{Res: DWORD; lphenum: thandle ;}
Res: = wnetopenenum (resource_globalnet, resourcetype_disk,
Resourceusage_container, nil, lphenum );
If res
(2) You can use the wnetenumresource API function
[0x21bd0000, 0x21bd0000, 0x221d0000)Tenured generation total 69632 K, used 2696 K [0x227d0000, 0x26bd0000, 0x26bd0000)The space 69632 K, 3% used[0x227d0000, 0x22a720f8, 0x22a72200, 0x26bd0000)Compacting perm gen total 8192 K, used 2898 K [0x26bd0000, 0x273d0000, 0x2abd0000)The space 8192 K, 35% used [0x26bd0000, 0x26ea4ba8, 0x26ea4c00, 0x273d0000)Ro space 8192 K
[0x1ebd0000, 0x227d0000, 0x227d0000)Eden space 49152 K, 99% used[0x1ebd0000, 0x21bce430, 0x21bd0000)From space 6144 K, 55% used[0x221d0000, 0x22527e10, 0x227d0000)To space 6144 K, 0% used [0x21bd0000, 0x21bd0000, 0x221d0000)Tenured generation total 69632 K, used 2696 K [0x227d0000, 0x26bd0000, 0x26bd0000)The space 69632 K, 3% used[0x227d0000, 0x22a720f8, 0x22a72200, 0x26bd0000)Compacting perm Gen total 8192 K, used 2898 K [0x26bd0000, 0x273d0000, 0x2
: Print the time when the program is suspended during garbage collection. Can be used together with the aboveOutput Format:Total time for which application threads were stopped: 0.0468229 seconds
-XX: printheapatgc: Print detailed stack information before and after GCOutput Format:34.702: [GC {heap before GC invocations = 7:Def New Generation total 55296 K, used 52568 K [0x1ebd0000, 0x227d0000, 0x227d0000)Eden space 49152 K, 99% used[0x1ebd0000, 0x21bce430, 0x21bd0000)From space 6144 K, 55% u
K, 99% used [0x1ebd0000, 0x21bce430, 0x21bd0000)
From space 6144 K, 55% used [0x221d0000, 0x22527e10, 0x227d0000)
To space 6144 K, 0% used [0x21bd0000, 0x21bd0000, 0x221d0000)
Tenured generation total 69632 K, used 2696 K [0x227d0000, 0x26bd0000, 0x26bd0000)
The space 69632 K, 3% used [0x227d0000, 0x22a720f8, 0x22a72200, 0x26bd0000)
Compacting perm Gen total 8192 K, used 2898 K [0x26bd0000, 0x273d0000, 0x2abd0000)
The space
) ); } /** * Accept data from client*/ Public functionRead$client _socket){ returnSocket_read ($client _socket, 8192);//8192 The actual representation of the accepted length, I use 819292 to indicate a bit longer, so that a longer string can also be accepted, less than 8192 is OK, will automatically identify }}$socket _server=Newsocketserver ();$socket _s
: Print the time when the program is suspended during garbage collection. Can be used together with the above
Output Format:Total time for which application threads were stopped: 0.0468229 seconds
-XX: PrintHeapAtGC: Print detailed stack information before and after GC
Output Format:
34.702: [GC {Heap before gc invocations = 7:
Def new generation total 55296 K, used 52568 K [0x1ebd0000, 0x227d0000, 0x227d0000)
Eden space 49152 K, 99% used[0x1ebd0000, 0x21bce430, 0x21bd0000)
From sp
1. 1. Run SQLshowparameterdb_block_sizeNAMETYPEVALUE in the Command window: ----------------------------------------------------------------------------- db_block_sizeinteger81922. 2. Run the following command in the SQL window: query the db_block_size (81) of the instance.
1. 1. run SQL show parameter db_block_size NAME TYPE VALUE ------------------------------------------ mongodb_block_size integer 8192 2 and 2 in the Command window: // query the db
of blocks to write. So if your disk is very small and very small files, such as 1k or 2k, it is recommended to format the disk when you specify a smaller number of blocks. Ext File system default block size is 4096 that is 4k. In the format, you can specify the block size is 1024, 2048, 4096 (they are multiplied), although the format can be specified when the block size of more than 4096, but once more than 4096 is not normal mount, how to specify the block size? [[emailprotected]~]#mke2fs-text
maximum available virtual memory for the process, in Kbytes
Ulimit–v 200000; Limit the maximum available virtual memory to 200000 Kbytes
Based on the table above, if you need to set the maximum number of processes and the number of open files for the current user, just set the following:
Ulimit-u 8192 Sets the maximum number of processes for the current user to 8192 and only takes ef
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