AW: Re: [squeak-dev] Adding fsync() call to the primitiveFileFlush prim ?

> On May 21, 2016, at 22:07, David T. Lewis <[hidden email]> wrote:
>
>> On Sat, May 21, 2016 at 10:49:24AM -0700, tim Rowledge wrote:
>> The issue here is that the PI - especially when used in schools - is storing everything on a micro-SD card. Being surrounded by kids is a scary thing for a computer. They don???t necessarily bother to do a nice system shutdown or even exit Scratch before yanking the power. Teachers don???t necessarily know to tell them to; lots of people doing their best with insufficient knowledge.
>
> D'oh, now I get it. I was not thinking of the case of yanking the power cord.
> I can well imagine that this might be a bit disruptive for normal process exit
> cleanups that are supposed to ensure that fflushed buffers actually make it
> to the disk-like media.
>
>> An interesting thing is that I ???remembered??? that we flush files when closing them but in fact we don???t.
>
> In a perfect world you do not need to flush a file when closing it, because
> closing it implies a flush (e.g. fclose performs an fflush). That said,
> yanking the power cord might introduce some imperfections.
>
> Dave
>
>

> Give me one serious reason why yanking the power cord _should_ punish the
> user.
>
> That it still does is just another incovenience. It's sooo backwards.
>
> Cheers,
>
> Herbert.
>
>
> -------- Ursprüngliche Nachricht --------
> Von: John Pfersich
> Datum:22.05.2016 07:36 (GMT+01:00)
> An: The general-purpose Squeak developers list
> Betreff: Re: [squeak-dev] Adding fsync() call to the primitiveFileFlush prim
> ?
>
>
>
>
> Sent from my iPad
>> On May 21, 2016, at 22:07, David T. Lewis <[hidden email]> wrote:
>>
>>> On Sat, May 21, 2016 at 10:49:24AM -0700, tim Rowledge wrote:
>>> The issue here is that the PI - especially when used in schools - is
>>> storing everything on a micro-SD card. Being surrounded by kids is a scary
>>> thing for a computer. They don???t necessarily bother to do a nice system
>>> shutdown or even exit Scratch before yanking the power. Teachers don???t
>>> necessarily know to tell them to; lots of people doing their best with
>>> insufficient knowledge.
>>
>> D'oh, now I get it. I was not thinking of the case of yanking the power
>> cord.
>> I can well imagine that this might be a bit disruptive for normal process
>> exit
>> cleanups that are supposed to ensure that fflushed buffers actually make
>> it
>> to the disk-like media.
>>
>>> An interesting thing is that I ???remembered??? that we flush files when
>>> closing them but in fact we don???t.
>>
>> In a perfect world you do not need to flush a file when closing it,
>> because
>> closing it implies a flush (e.g. fclose performs an fflush). That said,
>> yanking the power cord might introduce some imperfections.
>>
>> Dave
>>
>>
> And I don't think that people that yank the power cord should be catered to.
> If you do stupid things, you should pay the consequences. A computer isn't a
> toaster. And teachers should convey that to their students.
>
>
>

> On May 22, 2016, at 01:40, Herbert König <[hidden email]> wrote:
>
> Hi John,
>
> Guess it's a matter of time. Last time I looked we used punched cards, now we just close the lid of our laptop and expect it to do the right things. Give me one serious reason why yanking the power cord _should_ punish the user.
>
> That it still does is just another incovenience. It's sooo backwards.
>
> Cheers,
>
> Herbert.
>
>
> -------- Ursprüngliche Nachricht --------
> Von: John Pfersich
> Datum:22.05.2016 07:36 (GMT+01:00)
> An: The general-purpose Squeak developers list
> Betreff: Re: [squeak-dev] Adding fsync() call to the primitiveFileFlush prim ?
>
>
>
>
> Sent from my iPad
> > On May 21, 2016, at 22:07, David T. Lewis <[hidden email]> wrote:
> >
> >> On Sat, May 21, 2016 at 10:49:24AM -0700, tim Rowledge wrote:
> >> The issue here is that the PI - especially when used in schools - is storing everything on a micro-SD card. Being surrounded by kids is a scary thing for a computer. They don???t necessarily bother to do a nice system shutdown or even exit Scratch before yanking the power. Teachers don???t necessarily know to tell them to; lots of people doing their best with insufficient knowledge.
> >
> > D'oh, now I get it. I was not thinking of the case of yanking the power cord.
> > I can well imagine that this might be a bit disruptive for normal process exit
> > cleanups that are supposed to ensure that fflushed buffers actually make it
> > to the disk-like media.
> >
> >> An interesting thing is that I ???remembered??? that we flush files when closing them but in fact we don???t.
> >
> > In a perfect world you do not need to flush a file when closing it, because
> > closing it implies a flush (e.g. fclose performs an fflush). That said,
> > yanking the power cord might introduce some imperfections.
> >
> > Dave
> >
> >
> And I don't think that people that yank the power cord should be catered to. If you do stupid things, you should pay the consequences. A computer isn't a toaster. And teachers should convey that to their students.
>

> especially on a computer as slow as the Pi. I haven't used Squeak on a Pi, but on my MacBook, a save takes a few seconds, and I've got better things to do than stop working while the save takes place. And the save itself might leave the image in an unstable state.
>
> Sent from my iPhone
>
>> On May 22, 2016, at 01:40, Herbert König <[hidden email]> wrote:
>>
>> Hi John,
>>
>> Guess it's a matter of time. Last time I looked we used punched cards, now we just close the lid of our laptop and expect it to do the right things. Give me one serious reason why yanking the power cord _should_ punish the user.
>>
>> That it still does is just another incovenience. It's sooo backwards.
>>
>> Cheers,
>>
>> Herbert.
>>
>>
>> -------- Ursprüngliche Nachricht --------
>> Von: John Pfersich
>> Datum:22.05.2016 07:36 (GMT+01:00)
>> An: The general-purpose Squeak developers list
>> Betreff: Re: [squeak-dev] Adding fsync() call to the primitiveFileFlush prim ?
>>
>>
>>
>>
>> Sent from my iPad
>> > On May 21, 2016, at 22:07, David T. Lewis <[hidden email]> wrote:
>> >
>> >> On Sat, May 21, 2016 at 10:49:24AM -0700, tim Rowledge wrote:
>> >> The issue here is that the PI - especially when used in schools - is storing everything on a micro-SD card. Being surrounded by kids is a scary thing for a computer. They don???t necessarily bother to do a nice system shutdown or even exit Scratch before yanking the power. Teachers don???t necessarily know to tell them to; lots of people doing their best with insufficient knowledge.
>> >
>> > D'oh, now I get it. I was not thinking of the case of yanking the power cord.
>> > I can well imagine that this might be a bit disruptive for normal process exit
>> > cleanups that are supposed to ensure that fflushed buffers actually make it
>> > to the disk-like media.
>> >
>> >> An interesting thing is that I ???remembered??? that we flush files when closing them but in fact we don???t.
>> >
>> > In a perfect world you do not need to flush a file when closing it, because
>> > closing it implies a flush (e.g. fclose performs an fflush). That said,
>> > yanking the power cord might introduce some imperfections.
>> >
>> > Dave
>> >
>> >
>> And I don't think that people that yank the power cord should be catered to. If you do stupid things, you should pay the consequences. A computer isn't a toaster. And teachers should convey that to their students.
>>
>

> On Mon, May 23, 2016 at 08:06:21PM +0800, Ben Coman wrote:
>> On Mon, May 23, 2016 at 1:33 PM, John Pfersich <[hidden email]> wrote:
>> > On a Raspberry Pi, which is what we're talking about, yanking the power unceremoniously crashes the system. The
> Pi doesn't even have a power switch. You can shut down the OS before you power it down, but we're talking about a $3
> 5 computer with virtually no bells and whistles. A kid that yanks the power cord deserves what he or she gets. The r
> est of the OS isn't as forgiving.
>> >
>> > I hope that this saving the user from himself doesn't degrade to auto saving because the pauses caused by autosa
> ves can be deadly to productivity,
>>
>> Since IIUC Linux's fork() is copy-on-write, maybe the VM can fork() a
>> process to perform the autosave.  That might help avoid an obvious
>> pause, however I have no clue how overall performance might be
>> affected by the read-only-page-faults that copy the individual pages
>> that the ongoing processes write to.
>>
>> cheers -ben
>
>
>
> Do you mean like this?
>
>   UnixProcess class>>saveImageInBackgroundNicely
>      "Save image in a background OS process with lowered scheduling priority."
>
>      "UnixProcess saveImageInBackgroundNicely"
>
>      ^ self saveImageInBackground: self uniqueNameForSavedImage nice: true
>
>
> This has been available for over 10 years, but AFAIK nobody uses it. That
> leads me to suspect that aformentioned "deadly threat to productivity"
> may not really be as horrible as previously believed ;-)
>
> Dave
>
>

> On a Raspberry Pi, which is what we're talking about, yanking the power unceremoniously crashes the system. The Pi doesn't even have a power switch. You can shut down the OS before you power it down, but we're talking about a $35 computer with virtually no bells and whistles. A kid that yanks the power cord deserves what he or she gets. The rest of the OS isn't as forgiving.
>
> I hope that this saving the user from himself doesn't degrade to auto saving because the pauses caused by autosaves can be deadly to productivity, especially on a computer as slow as the Pi. I haven't used Squeak on a Pi, but on my MacBook, a save takes a few seconds, and I've got better things to do than stop working while the save takes place. And the save itself might leave the image in an unstable state.
>
> Sent from my iPhone
>
>> On May 22, 2016, at 01:40, Herbert König <[hidden email]> wrote:
>>
>> Hi John,
>>
>> Guess it's a matter of time. Last time I looked we used punched cards, now we just close the lid of our laptop and expect it to do the right things. Give me one serious reason why yanking the power cord _should_ punish the user.
>>
>> That it still does is just another incovenience. It's sooo backwards.
>>
>> Cheers,
>>
>> Herbert.
>>
>>
>> -------- Ursprüngliche Nachricht --------
>> Von: John Pfersich
>> Datum:22.05.2016 07:36 (GMT+01:00)
>> An: The general-purpose Squeak developers list
>> Betreff: Re: [squeak-dev] Adding fsync() call to the primitiveFileFlush prim ?
>>
>>
>>
>>
>> Sent from my iPad
>> > On May 21, 2016, at 22:07, David T. Lewis <[hidden email]> wrote:
>> >
>> >> On Sat, May 21, 2016 at 10:49:24AM -0700, tim Rowledge wrote:
>> >> The issue here is that the PI - especially when used in schools - is storing everything on a micro-SD card. Being surrounded by kids is a scary thing for a computer. They don???t necessarily bother to do a nice system shutdown or even exit Scratch before yanking the power. Teachers don???t necessarily know to tell them to; lots of people doing their best with insufficient knowledge.
>> >
>> > D'oh, now I get it. I was not thinking of the case of yanking the power cord.
>> > I can well imagine that this might be a bit disruptive for normal process exit
>> > cleanups that are supposed to ensure that fflushed buffers actually make it
>> > to the disk-like media.
>> >
>> >> An interesting thing is that I ???remembered??? that we flush files when closing them but in fact we don???t.
>> >
>> > In a perfect world you do not need to flush a file when closing it, because
>> > closing it implies a flush (e.g. fclose performs an fflush). That said,
>> > yanking the power cord might introduce some imperfections.
>> >
>> > Dave
>> >
>> >
>> And I don't think that people that yank the power cord should be catered to. If you do stupid things, you should pay the consequences. A computer isn't a toaster. And teachers should convey that to their students.
>>
>