[OpenIndiana-discuss] Shell to use?

[Chris]

On 2021-01-20 08:37, Bob Friesenhahn wrote:
> On Wed, 20 Jan 2021, Hung Nguyen Gia via openindiana-discuss wrote:
> 
>> Regardless of it's good behavior or not, this does give Linux a huge 
>> advantage over us.
>> The different is significant.
>> If we want to continue to keep our Solaris heritage and continue to 
>> ridicule Linux, then OK, it's fine.
> 
> I did not see anyone here "ridiculing" Linux.  Different decisions were made 
> based
> on the target market.  Solaris made decisions with a priority on robustness 
> and
> Linux made decisions with a priority to run on cheap hardware.
> 
> I use Linux on tiny hardware where there is tremendous memory over-commit 
> (as much
> as 120x) and it is a wonder that apps run at all (sometimes they run 
> exceedingly
> slowly).  It is nice that this is possible to do.
> 
> It is possible to disable over-commit in Linux but then even many desktop 
> systems
> would not succeed with initializing at all.
> 
> Memory allocation via mmap() is useful but there is a decision point as to 
> whether
> to allocate backing storage in the swap space or not. By default allocated 
> pages
> are zero and actual memory is not used until something writes data to the 
> page (at
> which point in time there is a "page fault" and the kernel allocates a real 
> memory
> page and initializes it with zeroed bytes).  Likewise memory which is 
> "duplicated"
> by fork() and its COW principle is not used until it has been modified.  So 
> Linux
> (by default) is very optimistic and assumes that the app will not actually 
> use the
> memory it requested, or might not ever modify memory inherited by the forked
> process.
> 
> If one is running a large database server or critical large apps then 
> relying on
> over-commit is not helpful since once the system even slightly runs out of
> resources, either an app, or the whole system needs to die.
> 
> IBM's AIX was the earliest system I recall where over-commit was common and
> processes were scored based on memory usage.  When the system ran short of 
> memory
> it would usually kill the largest process.
> 
> Linux has followed this same strategy and computes an OOM score for each 
> process.
> When the system runs out of "already" allocated memory, then a process has 
> to die,
> or the system needs to panic and reboot, or new activities must be 
> disallowed.
Another difference with Linux, at least as compared to FreeBSD; is that Linux 
favors
disk backing. IOW they'd rather keep RAM free. Whereas the BSDs would rather 
use RAM.
Granted, ZFS brings COW which helps. But when given a choice, why not choose 
RAM over
disk? It's *much* faster.

--Chris
> 
> Bob

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