Re: Making Lemonade (Floating-point format changes)

On 5/19/2024 2:48 PM, Chris M. Thomasson wrote:

On 5/18/2024 6:48 PM, EricP wrote:

Chris M. Thomasson wrote:

On 5/18/2024 6:40 AM, EricP wrote:

Chris M. Thomasson wrote:

On 5/17/2024 12:26 PM, EricP wrote:

>
I don't understand your question.
My comment was about the consequences of not pinning buffer pages
before starting an I/O. If those pages were for a mapped file stored
on a network device it won't be different.

>
For some reason this made me think about getting a blue screen of death due to too much non-paged memory being used by too many concurrent overlapped IO's on Windows.

>
That shouldn't happen as Windows tracks each process's non-paged pool
allocations and quotas and it should return an error when exceeded,
though I've never stress tested it.
>

>
I have, wrt NT 4.0 back in the day. It can get to a point where the system is totally unresponsive. Then, sometimes, dies. A shit load of concurrent overlapped io ops, malloc tends to return NULL, then the non-paged memory gets really bad...

>
What I have seen is due to what turned out to be a bug in Windows Defender
is that in monitoring my internet packets it would leak non-paged pool,
which then grows consuming more and more free pages all while the system
gets slower and slower, until finally it hangs and has to be rebooted.
The solution was to disable Windows Defender, but I only discovered that
by chance (random thrashing about).

 I have not seen that one yet. Remember Dr Watson?
 

I've only seen one blue screen in 30 years of using WinNT.
That was a "Page fault at raised IRQL" in the Microsoft TCP driver
(basically, a page fault occurred inside a driver, a big no-no)
back in the 1990's and the replacement driver was already available
on the Microsoft website.
>
>

 I cannot remember what service pack it was when I could trigger a totally unresponsive system what could actually blue screen the shit out of itself. I think it was SP3. It think it was on Workstation. The one that would limit the number of concurrent overlapped TransmitFile calls wrt IOCP. The Server version was unlimited... Well, it was limited wrt non-paged memory.
 

I remember a little test that Microsoft made wrt 50,000 concurrent OVERLAPPED ops in IOCP vs an event driven model actually creating a windows event per connection multiplexing WFMO in several threads. The event model did not perform as well, but it did not do too bad either. I wonder if I can still find that paper. Back in 2002 or something. Hard to remember right now.