11-14-2014
sort is a merge-sort, which has no need or use for gigantic memory buffers -- unless you want to use more memory than is available and eat into swap, that is. If you have very high-performance swap that can be useful. Otherwise, leave -buffer-size out and let it manage itself.
-parallel should be a big performance gain -- if you have enough memory that it doesn't need to thrash your disk, and fast enough disks to keep up. If not, it will just make things worse.
I don't see any something-for-nothing solutions here. You won't squeeze out anything but percents here and there unless you deal with the bottlenecks. Every time you tell it "use more resources" and it slows down, that's a bottleneck. Every time you tell it "use less files" and it speeds up, that's a bottleneck.
1) More RAM -- the more the OS can cache, the less it has to wait on the disk. Brute force, but there's a reason RAM is popular, it works really well.
2) A different temp space. If you put /tmp/ on a different disk spindle than the file you are sorting, you can get the bandwidth of two disks instead of splitting the bandwidth of one disk several ways (and eliminate a lot of disk thrashing time). It doesn't have to be /tmp/ of course, sort -T puts the files wherever you ask.
3) Faster swap. Eat up more RAM than you have available and depend on an SSD to make up the difference. This could be good, though sounds rather complicated to me.
Last edited by Corona688; 11-14-2014 at 12:29 PM..
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tmpfs(7FS) File Systems tmpfs(7FS)
NAME
tmpfs - memory based file system
SYNOPSIS
#include <sys/mount.h>
mount (special, directory, MS_DATA, "tmpfs", NULL, 0);
DESCRIPTION
tmpfs is a memory based file system which uses kernel resources relating to the VM system and page cache as a file system. Once mounted, a
tmpfs file system provides standard file operations and semantics. tmpfs is so named because files and directories are not preserved across
reboot or unmounts, all files residing on a tmpfs file system that is unmounted will be lost.
tmpfs file systems can be mounted with the command:
mount -F tmpfs swap directory
Alternatively, to mount a tmpfs file system on /tmp at multi-user startup time (maximizing possible performance improvements), add the
following line to /etc/vfstab:
swap -/tmp tmpfs - yes -
tmpfs is designed as a performance enhancement which is achieved by caching the writes to files residing on a tmpfs file system. Perfor-
mance improvements are most noticeable when a large number of short lived files are written and accessed on a tmpfs file system. Large com-
pilations with tmpfs mounted on /tmp are a good example of this.
Users of tmpfs should be aware of some constraints involved in mounting a tmpfs file system. The resources used by tmpfs are the same as
those used when commands are executed (for example, swap space allocation). This means that large sized tmpfs files can affect the amount
of space left over for programs to execute. Likewise, programs requiring large amounts of memory use up the space available to tmpfs. Users
running into this constraint (for example, running out of space on tmpfs) can allocate more swap space by using the swap(1M) command.
Another constraint is that the number of files available in a tmpfs file system is calculated based on the physical memory of the machine
and not the size of the swap device/partition. If you have too many files, tmpfs will print a warning message and you will be unable to
create new files. You cannot increase this limit by adding swap space.
Normal file system writes are scheduled to be written to a permanent storage medium along with all control information associated with the
file (for example, modification time, file permissions). tmpfs control information resides only in memory and never needs to be written to
permanent storage. File data remains in core until memory demands are sufficient to cause pages associated with tmpfs to be reused at which
time they are copied out to swap.
An additional mount option can be specified to control the size of an individual tmpfs file system.
SEE ALSO
df(1M), mount(1M), mount_tmpfs(1M), swap(1M), mmap(2), mount(2), umount(2), vfstab(4)
System Administration Guide: Basic Administration
DIAGNOSTICS
If tmpfs runs out of space, one of the following messages will display in the console.
directory: File system full, swap space limit exceeded
This message appears because a page could not be allocated while writing to a file. This can occur if tmpfs is attempting to write more
than it is allowed, or if currently executing programs are using a lot of memory. To make more space available, remove unnecessary
files, exit from some programs, or allocate more swap space using swap(1M).
directory: File system full, memory allocation failed
tmpfs ran out of physical memory while attempting to create a new file or directory. Remove unnecessary files or directories or install
more physical memory.
WARNINGS
Files and directories on a tmpfs file system are not preserved across reboots or unmounts. Command scripts or programs which count on this
will not work as expected.
NOTES
Compilers do not necessarily use /tmp to write intermediate files therefore missing some significant performance benefits. This can be
remedied by setting the environment variable TMPDIR to /tmp. Compilers use the value in this environment variable as the name of the direc-
tory to store intermediate files.
swap to a tmpfs file is not supported.
df(1M) output is of limited accuracy since a tmpfs file system size is not static and the space available to tmpfs is dependent on the swap
space demands of the entire system.
SunOS 5.10 9 Oct 1990 tmpfs(7FS)