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caf
·3 bulan yang lalu·discuss
[We can broadly trust the US government] not to promote broken encryption to its own agencies.
caf
·4 tahun yang lalu·discuss
Well, one might reasonably assume that the government has the means and motive to put forward their side of the case. Selling policy is kind of the main job of a politician, after all, and the government has a considerably large megaphone to do it with.
caf
·4 tahun yang lalu·discuss
You are saying that shareholders ought to hold this immense power that say Facebook has to move elections?

Certainly, if the alternative is that those in government get to wield it instead. I would wager I've considerably more trust in government and politicians than average - I do believe that in the main they're working very hard for what they perceive to be the greater good - but I draw the line at the politicians getting to directly control the political media.

Part of this is that I don't think Facebook's power alone is "immense" - but if you had all of the large media centrally controlled then you'd be getting there.

The very idea completely compromises those "bi-annual elections". How can you effectively challenge the state when all the large media is state-controlled?
caf
·4 tahun yang lalu·discuss
"through proxies" is doing a lot of heavy lifting here.

The alternative being suggested here seems to be to allow the regime to compel media outlet to publish their propaganda, because some don't like media outlets being able to choose the views they promote.
caf
·4 tahun yang lalu·discuss
So your solution to the worry that large social networks have the power to move elections, is to put that power in the hands of the people with the most incentive to move elections?
caf
·5 tahun yang lalu·discuss
Do you suppose handwritten assembly had a lesser rate of unexpected or unintended behaviour?
caf
·5 tahun yang lalu·discuss
Yes. For example, see this video of a Continuous Tamping Machine in operating, tamping railway ballast:

https://fb.watch/79KwlAt2Fz/

You probably wouldn't have to go too far back to find people sceptical about the possibility of automating that.
caf
·5 tahun yang lalu·discuss
Right. A working automated bricklaying machine would be like a C compiler for brickmasons.
caf
·7 tahun yang lalu·discuss
Reading large files using direct IO defeats kernel read-ahead, which means you have to take on the complexity of reimplementing it in userspace, or the performance hit of not having it.

This is a good reason for programs to use buffered IO even when they are reading a large file once, so yes my comment was entirely on point.
caf
·7 tahun yang lalu·discuss
I think it is pretty clear I was referring to kernel-mediated readahead. Sure, you can achieve the same thing in userspace using async IO or threads.
caf
·7 tahun yang lalu·discuss
It's not really that random. To see what the OOM killer heuristic currently considers its top 5 targets on your machine:

    for P in /proc/[0-9]*; do echo $(cat $P/oom_score) $(cat $P/comm); done | sort -n | tail -5
For me right now that shows 4 "Web Content" processes (firefox tabs) and a firefox-esr. That seems to check out.
caf
·7 tahun yang lalu·discuss
In this case the RW data (private dirty) can't be paged out even if cold because the OP is inadvisedly running without swap. This leaves the VM very few targets to drop.
caf
·7 tahun yang lalu·discuss
If you've foolishly decided to run without swap (like the original post), then suspending the offending program does nothing.

This is because the offending program has allocated a lot of private dirty pages, which can't be dropped from memory because without swap space, there is nowhere for it to go.
caf
·7 tahun yang lalu·discuss
Why can’t a user make QoS decisions for their own pages?

Because then you just get everyone asking for maximum QOS / don't-page-me-out on everything they can.

The pages in the page cache are not owned by a particular user, they're shared. If there's three users running /usr/bin/firefox, they'll all have have shared read-only executable mappings of the same page cache pages. If you do a buffered read of a file immediately after I do the same, we both get our data copied from the same page cache page. So it's not at all clear how you'd do the accounting on this to implement that user-based fairness criterion.
caf
·7 tahun yang lalu·discuss
If you are reading unbuffered (ie. O_DIRECT) then you are reading directly into the memory block the user supplied, so you cannot read ahead - there's nowhere to put the extra data.
caf
·7 tahun yang lalu·discuss
The problem I'm trying to point out here is that if the extra metadata in the page cache is entirely under user control (like for example "is mapped shared" and/or "is mapped executable") then it amounts to a user-specified QOS flag.

That might be OK on a single-user system but it doesn't fly on a multi-user one. That's why I suggested you could gate that kind of thing behind some kind of superuser control.
caf
·7 tahun yang lalu·discuss
There _NEEDS_ to be a setting where program pages don't get pushed out for disk cache, peroid, unless approaching a low ram situation, but BEFORE it causes long periods of total crushing unresponsiveness.

Here's the thing: a mapped program page is just another page in the page cache. Now, you could maybe say that "any page cache page that is mapped into at least one process will be pinned", but the problem there is that means that any unprivileged process can then pin an unlimited amount of memory, which is an obvious non-starter.

A workable alternative might be to add an extended file attribute like 'privileged.pinned_mapping', which if set indicates that any pages of the file that have active shared mappings are pinned. That means the superuser can go along and mark all the normal executables in this way, and the worst-case memory consumption a user can cause is limited by the total size of all the executables marked in this way that the user has access to.
caf
·7 tahun yang lalu·discuss
Readahead is still useful for large files read sequentially once, and that needs to be buffered. Such programs should use posix_fadvise().
caf
·8 tahun yang lalu·discuss
It accepts contactless payments over the threshold where a PIN is required, and does in fact prompt for a PIN using an on-screen keypad.
caf
·8 tahun yang lalu·discuss
Those VISA/MasterCard rules can't be universal because there's at least one bank issuing merchant terminals that run Android and take the PIN on the touchscreen:

https://www.commbank.com.au/business/merchant-services/eftpo...