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knc1 · 02-15-2016, 11:26 AM

On a KT (B00F - fw-5.3.7.3), 256Mbyte Ram, 4Gbyte eMMC ::

Using the system feature that /var/local is always mounted; either in 'main' or 'diags'.

Setup to use 1/4 of /var/local for a system swap file.

Over ssh (or telnet or serial port or from kTerm) -

Code:

[root@kindle root]# cd /var/local

[root@kindle local]# df .
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/mmcblk0p3           31729     13083     17008  43% /var/local

The Busybox/Ash command line can do simple math, find number of erase blocks:

Code:

[root@kindle local]# echo $((1024*1024*8/4096))
2048

Linux swap files **must** be initialized to zeros (no sparse files allowed):

Code:

[root@kindle local]# dd if=/dev/zero of=swap bs=4096 count=2048
2048+0 records in
2048+0 records out
8388608 bytes (8.0MB) copied, 0.186354 seconds, 42.9MB/s

The swap file requires a special format:

Code:

[root@kindle local]# mkswap ./swap
Setting up swapspace version 1, size = 8384 kB
no label, UUID=7b04d237-2476-4b2c-8b7b-0a5b58bf3006

The above completes the (one-time) setup of a K5 swapfile.
Its use by the system is controlled by the swapon and swapoff commands.

Code:

[root@kindle local]# swapon ./swap

[root@kindle local]# free
             total       used       free     shared    buffers     cached
Mem:        255660     248608       7052          0      30308      85580
-/+ buffers/cache:     132720     122940
Swap:         7852          0       7852

Now open Kindle User's Guide

Code:

[root@kindle local]# free
             total       used       free     shared    buffers     cached
Mem:        255660     247056       8604          0      22084      80048
-/+ buffers/cache:     144924     110736
Swap:         7852       2068       5784

Browse the user's guide, with and without per-page refresh enabled.
Then close Kindle User's Guide

Code:

[root@kindle local]# swapon -s
Filename            Type    Size    Used    Priority
/var/local/swap     file    7852    2056    -1

[root@kindle local]# df .
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/mmcblk0p3           31729     21306      8785  71% /var/local

For users with a lot of books, perhaps using only 4Mbyte (half the above size) for the swap file would be a better choice.
Even using only 2Mbyte of file space for the swap file reduces the kernel's page management workload.

To the end-user, the appearent change is a more responsive Kindle.

Since the above steps do not make an addition to /etc/fstab, the use of the swap file will 'go away' with the next re-boot.

That is: the 'swapon /var/local/swap' command needs to re-issued after each reboot (the normal system shutdown will take care of the 'swapoff' process).

When (IF) I get the spare time, I'll create a KUAL extension button (set) to let the non-technical user deal with all of the above.

Note 1:
If your 'main' system chokes by running out of space on /var/local -
just re-boot into 'diags' and remove the /var/local/swap file.

Note 2:
Other directions you find may say to put the swap file in user storage.
Not a good idea, because the Kernel can't access user storage when it is exported as mass storage over USB.
And the Kernel really, really does not like to have the backing store of its swap file suddenly disappear.

Note 3:
The KT is the earliest Kindle with a large enough /var/local partition to make the above practical.

02-15-2016, 11:26 AM	#1
knc1 Going Viral Posts: 17,212 Karma: 18210809 Join Date: Feb 2012 Location: Central Texas Device: No K1, PW2, KV, KOA	Using swap on a KT On a KT (B00F - fw-5.3.7.3), 256Mbyte Ram, 4Gbyte eMMC :: Using the system feature that /var/local is always mounted; either in 'main' or 'diags'. Setup to use 1/4 of /var/local for a system swap file. Over ssh (or telnet or serial port or from kTerm) - Code: [root@kindle root]# cd /var/local [root@kindle local]# df . Filesystem 1K-blocks Used Available Use% Mounted on /dev/mmcblk0p3 31729 13083 17008 43% /var/local The Busybox/Ash command line can do simple math, find number of erase blocks: Code: [root@kindle local]# echo $((102410248/4096)) 2048 Linux swap files must be initialized to zeros (no sparse files allowed): Code: [root@kindle local]# dd if=/dev/zero of=swap bs=4096 count=2048 2048+0 records in 2048+0 records out 8388608 bytes (8.0MB) copied, 0.186354 seconds, 42.9MB/s The swap file requires a special format: Code: [root@kindle local]# mkswap ./swap Setting up swapspace version 1, size = 8384 kB no label, UUID=7b04d237-2476-4b2c-8b7b-0a5b58bf3006 The above completes the (one-time) setup of a K5 swapfile. Its use by the system is controlled by the swapon and swapoff commands. Code: [root@kindle local]# swapon ./swap [root@kindle local]# free total used free shared buffers cached Mem: 255660 248608 7052 0 30308 85580 -/+ buffers/cache: 132720 122940 Swap: 7852 0 7852 Now open Kindle User's Guide Code: [root@kindle local]# free total used free shared buffers cached Mem: 255660 247056 8604 0 22084 80048 -/+ buffers/cache: 144924 110736 Swap: 7852 2068 5784 Browse the user's guide, with and without per-page refresh enabled. Then close Kindle User's Guide Code: [root@kindle local]# swapon -s Filename Type Size Used Priority /var/local/swap file 7852 2056 -1 [root@kindle local]# df . Filesystem 1K-blocks Used Available Use% Mounted on /dev/mmcblk0p3 31729 21306 8785 71% /var/local For users with a lot of books, perhaps using only 4Mbyte (half the above size) for the swap file would be a better choice. Even using only 2Mbyte of file space for the swap file reduces the kernel's page management workload. To the end-user, the appearent change is a more responsive Kindle. Since the above steps do not make an addition to /etc/fstab, the use of the swap file will 'go away' with the next re-boot. That is: the 'swapon /var/local/swap' command needs to re-issued after each reboot (the normal system shutdown will take care of the 'swapoff' process). When (IF) I get the spare time, I'll create a KUAL extension button (set) to let the non-technical user deal with all of the above. Note 1: If your 'main' system chokes by running out of space on /var/local - just re-boot into 'diags' and remove the /var/local/swap file. Note 2: Other directions you find may say to put the swap file in user storage. Not a good idea, because the Kernel can't access user storage when it is exported as mass storage over USB. And the Kernel really, really does not like to have the backing store of its swap file suddenly disappear. Note 3: The KT is the earliest Kindle with a large enough /var/local partition to make the above practical. Last edited by knc1; 02-15-2016 at 11:31 AM.