diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/blockdev/zram.txt | 71 | ||||
| -rw-r--r-- | Documentation/filesystems/proc.txt | 4 | ||||
| -rw-r--r-- | Documentation/filesystems/vfs.txt | 12 |
3 files changed, 75 insertions, 12 deletions
diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt new file mode 100644 index 00000000000..2eccddffa6c --- /dev/null +++ b/Documentation/blockdev/zram.txt @@ -0,0 +1,71 @@ +zram: Compressed RAM based block devices +---------------------------------------- + +* Introduction + +The zram module creates RAM based block devices named /dev/zram<id> +(<id> = 0, 1, ...). Pages written to these disks are compressed and stored +in memory itself. These disks allow very fast I/O and compression provides +good amounts of memory savings. Some of the usecases include /tmp storage, +use as swap disks, various caches under /var and maybe many more :) + +Statistics for individual zram devices are exported through sysfs nodes at +/sys/block/zram<id>/ + +* Usage + +Following shows a typical sequence of steps for using zram. + +1) Load Module: + modprobe zram num_devices=4 + This creates 4 devices: /dev/zram{0,1,2,3} + (num_devices parameter is optional. Default: 1) + +2) 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 + + # Using mem suffixes + echo 256K > /sys/block/zram0/disksize + echo 512M > /sys/block/zram0/disksize + echo 1G > /sys/block/zram0/disksize + +3) Activate: + mkswap /dev/zram0 + swapon /dev/zram0 + + mkfs.ext4 /dev/zram1 + mount /dev/zram1 /tmp + +4) Stats: + Per-device statistics are exported as various nodes under + /sys/block/zram<id>/ + disksize + num_reads + num_writes + invalid_io + notify_free + discard + zero_pages + orig_data_size + compr_data_size + mem_used_total + +5) Deactivate: + swapoff /dev/zram0 + umount /dev/zram1 + +6) Reset: + Write any positive value to 'reset' sysfs node + echo 1 > /sys/block/zram0/reset + echo 1 > /sys/block/zram1/reset + + This frees all the memory allocated for the given device and + resets the disksize to zero. You must set the disksize again + before reusing the device. + +Nitin Gupta +ngupta@vflare.org diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 31f76178c98..f00bee144ad 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -1386,8 +1386,8 @@ may allocate from based on an estimation of its current memory and swap use. For example, if a task is using all allowed memory, its badness score will be 1000. If it is using half of its allowed memory, its score will be 500. -There is an additional factor included in the badness score: root -processes are given 3% extra memory over other tasks. +There is an additional factor included in the badness score: the current memory +and swap usage is discounted by 3% for root processes. The amount of "allowed" memory depends on the context in which the oom killer was called. If it is due to the memory assigned to the allocating task's cpuset diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index deb48b5fd88..c53784c119c 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -782,7 +782,7 @@ struct file_operations ---------------------- This describes how the VFS can manipulate an open file. As of kernel -3.5, the following members are defined: +3.12, the following members are defined: struct file_operations { struct module *owner; @@ -803,9 +803,6 @@ struct file_operations { int (*aio_fsync) (struct kiocb *, int datasync); int (*fasync) (int, struct file *, int); int (*lock) (struct file *, int, struct file_lock *); - ssize_t (*readv) (struct file *, const struct iovec *, unsigned long, loff_t *); - ssize_t (*writev) (struct file *, const struct iovec *, unsigned long, loff_t *); - ssize_t (*sendfile) (struct file *, loff_t *, size_t, read_actor_t, void *); ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int); unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); int (*check_flags)(int); @@ -814,6 +811,7 @@ struct file_operations { ssize_t (*splice_read)(struct file *, struct pipe_inode_info *, size_t, unsigned int); int (*setlease)(struct file *, long arg, struct file_lock **); long (*fallocate)(struct file *, int mode, loff_t offset, loff_t len); + int (*show_fdinfo)(struct seq_file *m, struct file *f); }; Again, all methods are called without any locks being held, unless @@ -864,12 +862,6 @@ otherwise noted. lock: called by the fcntl(2) system call for F_GETLK, F_SETLK, and F_SETLKW commands - readv: called by the readv(2) system call - - writev: called by the writev(2) system call - - sendfile: called by the sendfile(2) system call - get_unmapped_area: called by the mmap(2) system call check_flags: called by the fcntl(2) system call for F_SETFL command |