Dirty words on linux-kernel

Dirty words on linux-kernel

[Jamie Lokier]

Sorry folks, but I found this bounce from a message I sent to
linux-kernel both funny and slightly disturbing.  Note that the bounce
comes from a subscriber to linux-kernel, not the mailing list
management! (:-)

  Subject: ScanMail Message: To Sender, sensitive content found and action taken.
  From: System Attendant <WLVEXC01-SA@digitalinsight.com>

  Trend SMEX Content Filter has detected sensitive content.

  Place = Linus Torvalds; Andrew Morton; lkml;
  Sender = Jamie Lokier
  Subject = Re: [patch 6/12] hold atomic kmaps across generic_file_read
  Delivery Time = August 10, 2002 (Saturday) 10:59:18
  Policy = Dirty Words
  Action on this mail = Quarantine message

  Warning message from administrator:
  Sender, Content filter has detected a sensitive e-mail.

I wonder if anyone can spot "Dirty Words" in the text below!  (I don't
see any).  The bounce doesn't say which message; it must be one of the
two below.

enjoy,
-- Jamie

----------------- possible dirty talk #1 --------------------

Linus Torvalds wrote:
> Imagine doing a
>
>       fstat(fd..)
>       buf = aligned_malloc(st->st_size)
>       read(fd, buf, st->st_size);
>
> and having it magically populate the VM directly with the whole file
> mapping, with _one_ failed page fault. And the above is actually a fairly
> common thing. See how many people have tried to optimize using mmap vs
> read, and what they _all_ really wanted was this "populate the pages in
> one go" thing.

This will only provide the performance benefic when `aligned_malloc'
return "fresh" memory, i.e. memory that has never been written to.

Assuming most programs use plain old `malloc', which could be taught to
align nicely, then the optimisation might occur when a program starts
up, but later on it's more likely to return memory which has been
written to and previously freed.  So the performance becomes
unpredictable.

But it's a nice way to optimise if you are _deliberately_ optimising a
user space program.  First call mmap() to get some fresh pages, then
call read() to fill them.  Slower on kernels without the optimisation,
fast on kernels with it. :-)

-- Jamie

----------------- possible dirty talk #2 --------------------

Linus Torvalds wrote:
> For people like that, wouldn't it be nice to just be able to tell them: if
> you do X, we guarantee that you'll get optimal zero-copy performance for
> reading a file.

Don't forget to include the need for mmap(... MAP_ANON ...) prior to the
read.

Given the user will need to establish a new mapping anyway, why pussy
foot around with subtleties?  Just add a MAP_PREFAULT flag to mmap(),
which reads the whole file and maps it before returning.

-- Jamie

Re: Dirty words on linux-kernel

[Jon Portnoy]

Look to me like it'd be "_pussy_ foot" in the second one. Didn't someone 
else get the same kind of message before? Was it from the same host?

On Sat, 10 Aug 2002, Jamie Lokier wrote:

> Sorry folks, but I found this bounce from a message I sent to
> linux-kernel both funny and slightly disturbing.  Note that the bounce
> comes from a subscriber to linux-kernel, not the mailing list
> management! (:-)
> 
>   Subject: ScanMail Message: To Sender, sensitive content found and action taken.
>   From: System Attendant <WLVEXC01-SA@digitalinsight.com>
> 
>   Trend SMEX Content Filter has detected sensitive content.
> 
>   Place = Linus Torvalds; Andrew Morton; lkml;
>   Sender = Jamie Lokier
>   Subject = Re: [patch 6/12] hold atomic kmaps across generic_file_read
>   Delivery Time = August 10, 2002 (Saturday) 10:59:18
>   Policy = Dirty Words
>   Action on this mail = Quarantine message
> 
>   Warning message from administrator:
>   Sender, Content filter has detected a sensitive e-mail.
> 
> I wonder if anyone can spot "Dirty Words" in the text below!  (I don't
> see any).  The bounce doesn't say which message; it must be one of the
> two below.
> 
> enjoy,
> -- Jamie
> 
> ----------------- possible dirty talk #1 --------------------
> 
> Linus Torvalds wrote:
> > Imagine doing a
> >
> >       fstat(fd..)
> >       buf = aligned_malloc(st->st_size)
> >       read(fd, buf, st->st_size);
> >
> > and having it magically populate the VM directly with the whole file
> > mapping, with _one_ failed page fault. And the above is actually a fairly
> > common thing. See how many people have tried to optimize using mmap vs
> > read, and what they _all_ really wanted was this "populate the pages in
> > one go" thing.
> 
> This will only provide the performance benefic when `aligned_malloc'
> return "fresh" memory, i.e. memory that has never been written to.
> 
> Assuming most programs use plain old `malloc', which could be taught to
> align nicely, then the optimisation might occur when a program starts
> up, but later on it's more likely to return memory which has been
> written to and previously freed.  So the performance becomes
> unpredictable.
> 
> But it's a nice way to optimise if you are _deliberately_ optimising a
> user space program.  First call mmap() to get some fresh pages, then
> call read() to fill them.  Slower on kernels without the optimisation,
> fast on kernels with it. :-)
> 
> -- Jamie
> 
> ----------------- possible dirty talk #2 --------------------
> 
> Linus Torvalds wrote:
> > For people like that, wouldn't it be nice to just be able to tell them: if
> > you do X, we guarantee that you'll get optimal zero-copy performance for
> > reading a file.
> 
> Don't forget to include the need for mmap(... MAP_ANON ...) prior to the
> read.
> 
> Given the user will need to establish a new mapping anyway, why pussy
> foot around with subtleties?  Just add a MAP_PREFAULT flag to mmap(),
> which reads the whole file and maps it before returning.
> 
> -- Jamie
> -
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> Please read the FAQ at  http://www.tux.org/lkml/
> 
> 

Re: Dirty words on linux-kernel

[Heinz Diehl]

On Sat Aug 10 2002, Jamie Lokier wrote:

> Given the user will need to establish a new mapping anyway, why pussy
                                                                  ^^^^^
> foot around with subtleties?

;)

-- 
# Heinz Diehl, 68259 Mannheim, Germany

Re: Dirty words on linux-kernel

[DervishD]

    Hi Jamie :))

>Sorry folks, but I found this bounce from a message I sent to
>linux-kernel both funny and slightly disturbing.

    Oh, just funny. According to some... person here in the list,
you're a twit and this filter solves a problem for you: your
obviously weak mind is using dirty words for expressions since you
cannot find a clean and religiously acceptable word.

    Now seriously ;)) This filter is plain censorship and your fail
has been namely:

>Given the user will need to establish a new mapping anyway, why pussy

    That 'pussy' has caused the filter to complain, but don't worry
about that, because your message will go to LKML without problems and
the one affected is that user that suffers the filter censorship, who
wouldn't be able to read your posts. The rest of the list will read
it without any problem :) Next time try to use 'charming little cat'
instead of 'pussy' XDDD And obviously don't use words like 'fuck',
'shit', 'elderberry' or 'nih' to avoid that filter :)

    Raúl