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Re: [pcp] Linux Swap Patch

To: Ken McDonell <kenj@xxxxxxxxxxxxxxxx>
Subject: Re: [pcp] Linux Swap Patch
From: Nathan Scott <nathans@xxxxxxxxxx>
Date: Tue, 5 Mar 2013 01:20:23 -0500 (EST)
Cc: pcp@xxxxxxxxxxx
Delivered-to: pcp@xxxxxxxxxxx
In-reply-to: <51350F9B.6040709@xxxxxxxxxxxxxxxx>
Reply-to: Nathan Scott <nathans@xxxxxxxxxx>
And just to close the loop here ...

----- Original Message -----
> This would seem to shwo the problem ...
> 
> kenj@bozo:~$ cat /proc/vmstat | egrep 'psw|pgpg'
> pgpgin 1555648
> pgpgout 1697692
> pswpin 0
> pswpout 0

Turns out pgpgin and pgpgout are unrelated to swap, these are
accounted in submit_bio() which is a generic "submit any old
I/O to the block layer" routine.  Its used in filesystems and
the VM (and when issuing swap I/O for that matter) and MD and
LVM/DM and DRBD, and the list goes on.  All over the shop.

So, from your values above your machine has never issued any
swap I/O since last boot.

> kenj@bozo:~$ pminfo -f swap.pagesin swap.pagesout swap.in swap.out

Also, swap.in and swap.out were in 2.4.x but removed in 2.6.x
kernels (metric was "count of swap operations" - now, only the
pages are counted).  swap.in and .out for modern Linux kernels
should just see PM_ERR_APPVERSION from pmdalinux.

cheers.

--
Nathan

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