[TUHS] signals and blocked in I/O

Dave Horsfall dave at horsfall.org
Sat Dec 2 02:01:32 AEST 2017


On Fri, 1 Dec 2017, Larry McVoy wrote:

> Does anyone remember the reason that processes blocked in I/O don't 
> catch signals?  When did that become a thing, was that part of the 
> original design or did that happen in BSD?

Something to do with pending DMA transfers?

> I'm asking because I'm banging on FreeBSD and I can wedge it hard, to 
> the point that it won't recover, by just beating on tons of memory.

That happens on my MacBook a lot :-)  It "only" has 4GB memory, the most 
it will ever take.  In the meantime, my FreeBSD server, pretty much 
running only Sendmail and Apache (and BIND), gets along just fine with 
just 512MB (yes, really; it does not run X or anything).

Sigh...  Sometimes I miss my old 11/40 with 124kw of memory and a handful 
of users, the biggest memory hog probably being NROFF (we didn't have VI, 
but used EM)...

Hey, anyone remember Editor for Mortals?  The author ought to be shot for 
naming something just one keystroke away from "rm file"...

-- 
Dave Horsfall DTM (VK2KFU)  "Those who don't understand security will suffer."


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