Re: New RAM, does Debian has a tool to benchmark?
On 10.04.20 08:26, dalios wrote:
(...)
CPU Cache: 3 MB
(...)
Working with much older hardware than you and using Debian as a Desktop
with GUI (KDE) and not as a Server, I found the CPU Cache to be the most
important piece of hardware letting you "feel" your desktop "responding"
slow or fast. Nowadays I claim that 1 MB of cache is insufficient for
experiencing a satisfying "responsiveness" when interactively working
with the desktop. I do have a system with 2 MB cache and it is "usable",
although not "comfortable". My 3 MB cache system is fine and I am
working with it as my main system for my daily work, using heavily
Firefox with usually some 5 to 15 tabs open AND additionally having a
second Firefox with a different Firefox profile open for there running
web apps of Microsoft Office 365 in usually 3 tabs. In parallel I always
have open Thunderbird, RIOT (the matrix.org messenger client),
Cherrytree, Kate, and some times also LibreOffice Writer or even ImageJ
for some scientific image processing. This system has (only) the
following hardware specifications and runs all this:
CPU: Intel Core2Duo P7450 2.13 GHz
Cache: 3 MB
RAM: 4 GB
Note that my 1 MB, 2 MB and 3 MB CPU Cache systems all have an almost
identical CPU of type Core2Duo and CPU speed, and I also have another 2
MB CPU cache system with a slower CPU speed. I clearly "feel" strongly
the different amount of cache at my hands, but I do not feel the CPU
frequency differences!
The last hardware upgrade was to recently extend it to now have 2x 4 GB
RAM, but this was more because of having received the RAM free of cost
than having felt a need to search for it. Instead, what really becomes
an every day annoyance is a missing USB3 port, with the desire to have
USB3 Gen2 available for the necessary (highly recommended) everyday data
backup to some external storage media.
What I am about to say: with your hardware I would not worry too much
about benchmarking the RAM. Simply add as much RAM as you can, following
other people recommendations on how to best combine them (which RAM
mounted to which slot of your motherboard), but then instead of loosing
time with benchmarking better spend time on fine tuning some parameters
which are needed to adjust in order to let Debian run with nice
"responsiveness" as a desktop on not so fast hardware. Keep in mind,
that not used RAM is a waste of resources. If your system is constantly
using as much RAM as possible, but of course without ever to start to
swap data to slow bulk storage media, then it best uses your hardware
for you. Linux is intelligent towards this goal. It uses free RAM and
there caches data which you might need again, in order to then be able
to deliver you this data quickest. If your activity, some application,
needs the RAM, then immediately some cached data is thrown away (cached
data is considered to be able to become loaded in newly, if needed) and
the freed RAM is immediately available for your activity. So, the cache
will not impact your application's needs. Cache is used when possible
and not used when there is no vacancy for it. Now, this explains why you
will always see high RAM usage on your system. Whatever is unused by the
user activity will be used for a performance increase and for this will
be filled by the cache system. If you have 4 GB mounted to your
hardware, then it will be used almost completely, and if you now mount 8
GB (or 12 GB) to it, then you will (and want to) see that the 8 GB (or
12 GB) are used almost completely. Nice!
I always consider Debian to be the Linux distribution which
out-of-the-box comes well tuned for server applications, while not being
preconfigured nicely for desktop usage. The configurations which in this
regard I am mainly having in mind are the ones which adjust how the
Linux cache system should work, how the RAM which is not used by your
applications is meanwhile used. Afterwards it might also be worth to
consider the many logs and statistics which by the Debian default
configuration become generated, and how I/O to the bulk storage media is
used, but for the moment I won't have a look at that.
For now, maybe simply consider to adjust the following parameters for
the cache system and see if your system comforts you better:
create a file /etc/sysctl.d/99-SettingsByMyself.conf with the
following content, which will adjust the 2 main parameters
"vm.swappiness" and "vm.vfs_cache_pressure" influencing the cache system
towards the needs of running a Desktop with GUI on not so fast hardware:
# responsiveness of system preferred over data treatment speed:
# decrease from default=60 towards 0
# or
# data treatment speed preferred over responsiveness of system:
# increase from default=60 towards 100
#
# 0 = disable any swap activity
# 1 = minimum swap activity, helps to avoid running out of RAM
vm.swappiness = 1
# lower value in order to prefer inode/dentry cache to stay in cache
# for finding files faster; (default=100) (could be > 100)
vm.vfs_cache_pressure=25
Good Luck! Marco.
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