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From: "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com>
Newsgroups: comp.arch
Subject: Re: Making Lemonade (Floating-point format changes)
Date: Sun, 19 May 2024 14:55:38 -0700
Organization: A noiseless patient Spider
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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.