Bugzilla Bug 206773

Instead of only PORTAGE_NICENESS it would be nice if one could also set
IONICENESS and give the emerge process a lower io-nice value. Because even with
low CPU priority, heavy IO can still reduce the responsiveness of the system
alot.

Reproducible: Always

This is quite more complicated than nice as AFAIK there is no python function
available to do that, and using the external tool (which isn't installed on a
base system) is more complicated if the semantics should be the same as with
PORTAGE_NICENESS.
In short, if anyone wants to submit a patch for this feature we'll consider it,
but I don't think we'll implement this on our own.

Created an attachment (id=151724) [details]
Adds the ionice (ioniceness) feature

Setting ionice (ioniceness) for portage in /etc/make.conf
PORTAGE_IONICE_CLASS=<realtime|besteffort|idle|none>
PORTAGE_IONICE_PRIO=<0..7>

If the program ionice is not installed on the system, nothing happens. If the
settings are not defined in make.conf, nothing happens. If the settings contain
invalid values a message is printed. The binary must be located in PATH.

I second this, along with a "nice network io limiting" feature.

Such as when emerge fetches, it hogs the entire network and makes browsing with
firefox/browser unbearably slow!!!

/me casts my vote for this FEATURE!

Looks like the network limiting is already taken care of.  Sorry.
(http://gentoo-wiki.com/Emerge/Limit_bandwidth)

This ionice feature really needs to be integrated.

As I tend to also like to use nice (as well as ionice) on /etc/cron.d
processes, just finished integrating ionice into cron.  

According to:
http://gentoo-wiki.com/HOWTO_Light_Gentoo_Installation

I added an nice alias to /root/.bashrc including ionice according to the above
url ionice tip.  Felt creating a new /bin/nice was more of a hack.  At least
using /root/.bashrc is less of a hack, but still easily/commonly a
lost/forgotten setting!

Might be nice to just use "nice" alias/variable throughout the /etc/cron.d
files as well /etc/make.conf.  And then create a system wide /etc/nice.conf
setting how the admin wants this computer, whether server or client, to react
when running root services such as emerge processes (such as sync or regular
emerge) or when cron services are run such as /etc/cron.d/weekly/prelink, 
/etc/cron.d/weekly/locate, etc... <shrugs> ...  just my random thoughts on
centralizing this tools customizations.  Might also be a great idea to include
user io quotas within such a file as /etc/nice.conf.  <shrugs> 

Created an attachment (id=161266) [details]
add a PORTAGE_IONICE_COMMAND variable

Add a new PORTAGE_IONICE_COMMAND variable that emerge uses to adjust ionice
priority, similar to PORTAGE_NICENESS but used more like FETCHCOMMAND since so
that portage doesn't have to know anything about ionice options. The command
should include a \${PID} place-holder to be substituted with an integer pid.

The PORTAGE_IONICE_COMMAND patch is in svn.

Sweet!  Think a lot of people are going to enjoy this feature!

I've worked my systems over here utilizing ionice already.  Love having a
system that is still usable for compiling, etc, even while syncing remote &
local Portages across my platforms.  (I've also familarized myself with network
bandwidth quota using wget's custom command options within /etc/make.conf
recently.  Although, it'd probably be nicer seeing a simpler system wide
equivalent of ionice for network bandwidth quotas then manually messing with
network stack.)

This is fixed in 2.2_rc4.

And, if I'm not mistaken since =sys-apps/portage-2.1.5.6 is now the first
successive version release since rc4, it's now in "2.1.5.6" correct?

Err.  Or should this feature be included in portage-2.3 release?

(BTW, been on rc4 and it builds, works and does not seem to complain about the
IONICE function in make.conf.  Whether it's actually using it, i can't tell.)

portage-2.1.5.6 is an older (dead) branch and doesn't contain any new stuff,
except a few things that are new relative to 2.1.4.4. You have to use a 2.2_rc
release to get the latest features.

Also, PORTAGE_IONICE_COMMAND is disabled by default now (since 2.2_rc6) because
the behavior of various kernels wrt user privileges and ionice varies too much
(with some kernels you have to be root and emerge can do lots of things without
being root, like --buildpkgonly).

"Also, PORTAGE_IONICE_COMMAND is disabled by default now (since 2.2_rc6)"

In otherwords, PORTAGE_IONICE_COMMAND is commented-out within /etc/make.conf,
hence, leaving it unactive until removing the comment/pound sign character?

Right, you need something like this in make.conf to enable it:

PORTAGE_IONICE_COMMAND="ionice -c 3 -p \${PID}"