diff options
Diffstat (limited to 'Documentation/blockdev')
| -rw-r--r-- | Documentation/blockdev/cpqarray.txt | 93 | ||||
| -rw-r--r-- | Documentation/blockdev/zram.txt | 90 |
2 files changed, 45 insertions, 138 deletions
diff --git a/Documentation/blockdev/cpqarray.txt b/Documentation/blockdev/cpqarray.txt deleted file mode 100644 index c7154e20e..000000000 --- a/Documentation/blockdev/cpqarray.txt +++ /dev/null @@ -1,93 +0,0 @@ -This driver is for Compaq's SMART2 Intelligent Disk Array Controllers. - -Supported Cards: ----------------- - -This driver is known to work with the following cards: - - * SMART (EISA) - * SMART-2/E (EISA) - * SMART-2/P - * SMART-2DH - * SMART-2SL - * SMART-221 - * SMART-3100ES - * SMART-3200 - * Integrated Smart Array Controller - * SA 4200 - * SA 4250ES - * SA 431 - * RAID LC2 Controller - -It should also work with some really old Disk array adapters, but I am -unable to test against these cards: - - * IDA - * IDA-2 - * IAES - - -EISA Controllers: ------------------ - -If you want to use an EISA controller you'll have to supply some -modprobe/lilo parameters. If the driver is compiled into the kernel, must -give it the controller's IO port address at boot time (it is not -necessary to specify the IRQ). For example, if you had two SMART-2/E -controllers, in EISA slots 1 and 2 you'd give it a boot argument like -this: - - smart2=0x1000,0x2000 - -If you were loading the driver as a module, you'd give load it like this: - - modprobe cpqarray eisa=0x1000,0x2000 - -You can use EISA and PCI adapters at the same time. - - -Device Naming: --------------- - -You need some entries in /dev for the ida device. MAKEDEV in the /dev -directory can make device nodes for you automatically. The device setup is -as follows: - -Major numbers: - 72 ida0 - 73 ida1 - 74 ida2 - 75 ida3 - 76 ida4 - 77 ida5 - 78 ida6 - 79 ida7 - -Minor numbers: - b7 b6 b5 b4 b3 b2 b1 b0 - |----+----| |----+----| - | | - | +-------- Partition ID (0=wholedev, 1-15 partition) - | - +-------------------- Logical Volume number - -The device naming scheme is: -/dev/ida/c0d0 Controller 0, disk 0, whole device -/dev/ida/c0d0p1 Controller 0, disk 0, partition 1 -/dev/ida/c0d0p2 Controller 0, disk 0, partition 2 -/dev/ida/c0d0p3 Controller 0, disk 0, partition 3 - -/dev/ida/c1d1 Controller 1, disk 1, whole device -/dev/ida/c1d1p1 Controller 1, disk 1, partition 1 -/dev/ida/c1d1p2 Controller 1, disk 1, partition 2 -/dev/ida/c1d1p3 Controller 1, disk 1, partition 3 - - -Changelog: -========== - -10-28-2004 : General cleanup, syntax fixes for in-kernel driver version. - James Nelson <james4765@gmail.com> - - -1999 : Original Document diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt index 5bda5031c..0535ae1f7 100644 --- a/Documentation/blockdev/zram.txt +++ b/Documentation/blockdev/zram.txt @@ -59,34 +59,23 @@ num_devices parameter is optional and tells zram how many devices should be pre-created. Default: 1. 2) Set max number of compression streams - Compression backend may use up to max_comp_streams compression streams, - thus allowing up to max_comp_streams concurrent compression operations. - By default, compression backend uses single compression stream. - - Examples: - #show max compression streams number +Regardless the value passed to this attribute, ZRAM will always +allocate multiple compression streams - one per online CPUs - thus +allowing several concurrent compression operations. The number of +allocated compression streams goes down when some of the CPUs +become offline. There is no single-compression-stream mode anymore, +unless you are running a UP system or has only 1 CPU online. + +To find out how many streams are currently available: cat /sys/block/zram0/max_comp_streams - #set max compression streams number to 3 - echo 3 > /sys/block/zram0/max_comp_streams - -Note: -In order to enable compression backend's multi stream support max_comp_streams -must be initially set to desired concurrency level before ZRAM device -initialisation. Once the device initialised as a single stream compression -backend (max_comp_streams equals to 1), you will see error if you try to change -the value of max_comp_streams because single stream compression backend -implemented as a special case by lock overhead issue and does not support -dynamic max_comp_streams. Only multi stream backend supports dynamic -max_comp_streams adjustment. - 3) Select compression algorithm - Using comp_algorithm device attribute one can see available and - currently selected (shown in square brackets) compression algorithms, - change selected compression algorithm (once the device is initialised - there is no way to change compression algorithm). +Using comp_algorithm device attribute one can see available and +currently selected (shown in square brackets) compression algorithms, +change selected compression algorithm (once the device is initialised +there is no way to change compression algorithm). - Examples: +Examples: #show supported compression algorithms cat /sys/block/zram0/comp_algorithm lzo [lz4] @@ -94,17 +83,27 @@ max_comp_streams adjustment. #select lzo compression algorithm echo lzo > /sys/block/zram0/comp_algorithm +For the time being, the `comp_algorithm' content does not necessarily +show every compression algorithm supported by the kernel. We keep this +list primarily to simplify device configuration and one can configure +a new device with a compression algorithm that is not listed in +`comp_algorithm'. The thing is that, internally, ZRAM uses Crypto API +and, if some of the algorithms were built as modules, it's impossible +to list all of them using, for instance, /proc/crypto or any other +method. This, however, has an advantage of permitting the usage of +custom crypto compression modules (implementing S/W or H/W compression). + 4) Set Disksize - Set disk size by writing the value to sysfs node 'disksize'. - The value can be either in bytes or you can use mem suffixes. - Examples: - # Initialize /dev/zram0 with 50MB disksize - echo $((50*1024*1024)) > /sys/block/zram0/disksize +Set disk size by writing the value to sysfs node 'disksize'. +The value can be either in bytes or you can use mem suffixes. +Examples: + # Initialize /dev/zram0 with 50MB disksize + echo $((50*1024*1024)) > /sys/block/zram0/disksize - # Using mem suffixes - echo 256K > /sys/block/zram0/disksize - echo 512M > /sys/block/zram0/disksize - echo 1G > /sys/block/zram0/disksize + # Using mem suffixes + echo 256K > /sys/block/zram0/disksize + echo 512M > /sys/block/zram0/disksize + echo 1G > /sys/block/zram0/disksize Note: There is little point creating a zram of greater than twice the size of memory @@ -112,20 +111,20 @@ since we expect a 2:1 compression ratio. Note that zram uses about 0.1% of the size of the disk when not in use so a huge zram is wasteful. 5) Set memory limit: Optional - Set memory limit by writing the value to sysfs node 'mem_limit'. - The value can be either in bytes or you can use mem suffixes. - In addition, you could change the value in runtime. - Examples: - # limit /dev/zram0 with 50MB memory - echo $((50*1024*1024)) > /sys/block/zram0/mem_limit +Set memory limit by writing the value to sysfs node 'mem_limit'. +The value can be either in bytes or you can use mem suffixes. +In addition, you could change the value in runtime. +Examples: + # limit /dev/zram0 with 50MB memory + echo $((50*1024*1024)) > /sys/block/zram0/mem_limit - # Using mem suffixes - echo 256K > /sys/block/zram0/mem_limit - echo 512M > /sys/block/zram0/mem_limit - echo 1G > /sys/block/zram0/mem_limit + # Using mem suffixes + echo 256K > /sys/block/zram0/mem_limit + echo 512M > /sys/block/zram0/mem_limit + echo 1G > /sys/block/zram0/mem_limit - # To disable memory limit - echo 0 > /sys/block/zram0/mem_limit + # To disable memory limit + echo 0 > /sys/block/zram0/mem_limit 6) Activate: mkswap /dev/zram0 @@ -183,6 +182,7 @@ mem_limit RW the maximum amount of memory ZRAM can use to store pages_compacted RO the number of pages freed during compaction (available only via zram<id>/mm_stat node) compact WO trigger memory compaction +debug_stat RO this file is used for zram debugging purposes WARNING ======= |