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Full Discussion: Scan Rates
Operating Systems AIX Scan Rates Post 302307784 by zaxxon on Thursday 16th of April 2009 10:29:18 AM
Old 04-16-2009
3k pages as scan rate per sec is no big value. I sometimes see bigger ones. Usually it's the ratio/relation between scanned pages and freed pages that matters. Optimal to ok should be ratio fr/sr of ~ 1:1 - 1:3 afaik; can be but must not.

From some IBM AIX Performance Management Guide, note the last line in bold letters:
Quote:
# fr

Number of pages that were freed per second by the page-replacement algorithm during the interval. As the VMM page-replacement routine scans the Page Frame Table (PFT), it uses criteria to select which pages are to be stolen to replenish the free list of available memory frames. The criteria include both kinds of pages, working (computational) and file (persistent) pages. Just because a page has been freed, it does not mean that any I/O has taken place. For example, if a persistent storage (file) page has not been modified, it will not be written back to the disk. If I/O is not necessary, minimal system resources are required to free a page.
# sr

Number of pages that were examined per second by the page-replacement algorithm during the interval. The VMM page-replacement code scans the PFT and steals pages until the number of frames on the free list is at least the maxfree value. The page-replacement code might have to scan many entries in the PFT before it can steal enough to satisfy the free list requirements. With stable, unfragmented memory, the scan rate and free rate might be nearly equal. On systems with multiple processes using many different pages, the pages are more volatile and disjoint. In this scenario, the scan rate might greatly exceed the free rate.

Memory is over committed when the ratio of fr to sr (fr:sr) is high.

An fr:sr ratio of 1:4 means that for every page freed, four pages had to be examined. It is difficult to determine a memory constraint based on this ratio alone, and what constitutes a high ratio is workload/application dependent.

For tuning in general and to get a first impression, you should look at the output from "vmstat 1 20" for example at busy times. Just looking at "sr" will show/mean nothing.
 

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XWAX(1) 						      General Commands Manual							   XWAX(1)

NAME
xwax - Digital vinyl on Linux SYNOPSIS
xwax [options] DESCRIPTION
xwax is vinyl emulation software for Linux. It allows DJs and turntablists to playback digital audio files (MP3, Ogg Vorbis, FLAC, AAC and more), controlled using a normal pair of turntables via timecoded vinyls. OPTIONS
The ordering of options is important; many options apply to to subsequent music libraries or decks, which can be given multiple times. See the EXAMPLES below. -l path Scan the music library at the given path. -p path Load a playlist at the given path. This operation is identical to scanning a music library except that the order is defined by the output of the scanner executable. -t name Use the named timecode for subsequent decks. See -h for a list of valid timecodes. You will need the corresponding timecode signal on vinyl to control playback. -33 Set the reference playback speed for subsequent decks to 33 and one third revolutions per minute. This is the default. -45 Set the reference playback speed for subsequent decks to 45 revolutions per minute. -i path Use the given importer executable for subsequent decks. -s path Use the given scanner executable to scan subsequent music libraries. -h Display the help message and default values. ALSA DEVICE OPTIONS
The following options are available only when xwax is compiled with ALSA support. -a device Create a deck which uses the given ALSA device (eg. plughw:0). -r hz Set the sample rate for subsequent decks. -m milliseconds Set the ALSA buffer time for subsequent decks. JACK DEVICE OPTIONS
The following options are available only when xwax is compiled with JACK support. -j name Create a deck which connects to JACK and registers under the given name. xwax does not set the sample rate for JACK devices; it uses the sample rate given in the global JACK configuration. OSS DEVICE OPTIONS
The following options are available only when xwax is compiled with OSS support. -d pathname Create a deck which uses the given OSS device (eg. /dev/dsp). -r hz Set the sample rate for subsequent decks. -b n Set the number of OSS buffers for subsequent decks. -f n Set the OSS buffer size (2^n bytes). CONTROLS
The playback of each deck (direction, speed and position) is controlled via the incoming timecode signal from the turntables. The keyboard provides additional controls. Record selection controls: cursor up, cursor down Move highlighted record up/down by one. page up, page down Scroll the record listing up/down by one page. left cursor, right cursor Switch to the previous/next crate of records. tab Toggle between the current crate and the 'All records' crate. To filter the current list of records type a portion of a record name. Separate multiple searches with a space, and use backspace to delete. Deck-specific controls: Deck 0 Deck 1 Deck 2 F1 F5 F9 Load currently selected track to this deck F2 F6 F10 Reset start of track to the current position F3 F7 F11 Toggle timecode control on/off Audio display controls: +, - Zoom in/out the close-up audio meters for all decks. EXAMPLES
2-deck setup using one directory of music and OSS devices: xwax -l ~/music -d /dev/dsp -d /dev/dsp1 As above, but using ALSA devices: xwax -l ~/music -d hw:0 -d hw:1 2-deck setup using a different timecode on each deck: xwax -l ~/music -t serato_2a -d hw:0 -t mixvibes_v2 -d hw:1 As above, but with the second deck at 45 RPM: xwax -l ~/music -t serato_2a -d hw:0 -t mixvibes_v2 -45 -d hw:1 3-deck setup with the third deck at a higher sample rate: xwax -l ~/music -r 48000 -a hw:0 -a hw:1 -r 96000 -a hw:2 Using all three device types simultaneously, one deck on each: xwax -l ~/music -a hw:0 -d /dev/dsp1 -j jack0 Scan multiple music libraries: xwax -l ~/music -l ~/sounds -l ~/mixes -a hw:0 Scan a second music library using a custom script: xwax -l ~/music -i ./custom-scan -l ~/sounds -a hw:0 HOMEPAGE
http://www.xwax.co.uk/ AUTHOR
Mark Hills <mark@pogo.org.uk> XWAX(1)
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