Active Topics

 


Page 3 of 5 12 3 45
Reply
Thread Tools
epitaph is offline epitaph
2011-01-19 , 17:54
Banned | Posts: 358 | Thanked: 160 times | Joined on Dec 2010
#21
Originally Posted by atilla View Post
yes if you trusts in such crap its your fault.
if he upload a video where he is downloading with 600kbps and there is no lag i will send him my n900
I did it to. Not this mod but my tune-up utilities! 600 kpbs is not a problem its a nice device from nokia!
 
woody14619's Avatar
woody14619 is offline woody14619
2011-01-19 , 18:11
Posts: 1,455 | Thanked: 3,309 times | Joined on Dec 2009 @ Rochester, NY
#22
Originally Posted by atunguyd View Post
Be careful here - I am lead to believe that the N900 has a magnetic sensor that detects when the back plate has been removed and automatically un-mounts the SD card.
This is correct, but not as disastrous as it sounds. Unix won't let you (even as root) unmount a file system that has something going on in it. The automated scripts may try to kill all fusers of the device, but if the thing using it is the swapper, it can't kill that, so there's no way it would unmount.

Even if Maemo has some funky hack that lets it (unlikely), if you setup the swap space as a partition (vs file-based swap), it could unmount the fs on the card all it wants. Swap partitions aren't "mounted", but are turned on or off at the kernel level. Swap partitions have no real "format", just a header indicating their size. All the swap allocation information is kept in real memory.

Now if you were to open the back cover and remove the card while it's swapping to it, then you're hosed... Don't do that.

Originally Posted by gerdich View Post
Is it impossible to construct an sd card with real dedicated RAM
(e.g. a buffer of 512MBytes RAM)?
Actually, it's quite possible, if you have access to a fabrication lab and the equipment needed to do so. There are some companies that make SD cards with built in wifi and micro controllers in them. They look like normal memory cards to the host, but when near wifi and powered on, they can auto-upload your images to flicr or facebook or the like.

But unless you're a micro-E student, or work in a business that has micro-fab facilities, you're out of luck. If you do, be prepared for some expensive component and fabrication costs. You'll need to make it SDRAM at least, and will need to tweek the slot driver to not go into a total sleep state to keep enough power going to it to not lose memory. (So it would be a slight battery drain too...)

With the speed of flash writing (with 12x cards available), the cost of real ram would be tough to validate. Especially since most devices wouldn't be able to use it, since most aren't as tweakable. If you do have access to such a service though, may as well make a die of them. I'm sure you could sell the extras to forum members after showing they're valid.
 
Khertan's Avatar
Khertan is offline Khertan
2011-01-19 , 18:18
Posts: 1,012 | Thanked: 817 times | Joined on Jul 2007 @ France
#23
Haha ... you lie

Do a simple cat /proc/meminfo and read the value ... Swap is limited by the kernel, at a value under 1Gb
__________________
Benoît HERVIER, Khertan
KhtEditor - Sdist_Maemo - Khweeteur - PyPackager - KhtSimpleText - KhtNotes - KhtBMA - Wleux - and more ...
 
Khertan's Avatar
Khertan is offline Khertan
2011-01-19 , 18:27
Posts: 1,012 | Thanked: 817 times | Joined on Jul 2007 @ France
#24
Originally Posted by wmarone View Post
Yes.

And you get the longer explanation:

SD Cards can at best provide flash-based swap. Since an SD card is basically extra thin PCB-style substrate with a NAND die on top, controller, and covered by plastic, it's not feasible to modify one to provide RAM and none are made to provide it.

Extra long explanation yours courtesy of "Yes" being too short for the forum software

It s possible to do one with ddr instead of using a Nand, but will probably require a microcontroller to manage it, and require a permanent power. Drain battery, reset of the filesystem on power off ... And will probably be slower due to the microcontroller managing thing
__________________
Benoît HERVIER, Khertan
KhtEditor - Sdist_Maemo - Khweeteur - PyPackager - KhtSimpleText - KhtNotes - KhtBMA - Wleux - and more ...
 
retsaw is offline retsaw
2011-01-19 , 19:30
Posts: 701 | Thanked: 585 times | Joined on Sep 2010 @ London, England
#25
Originally Posted by woody14619 View Post
Originally Posted by atunguyd View Post
Originally Posted by Be careful here - I am lead to believe that the N900 has a magnetic sensor that detects when the back plate has been removed and automatically un-mounts the SD card.
This is correct, but not as disastrous as it sounds. Unix won't let you (even as root) unmount a file system that has something going on in it. The automated scripts may try to kill all fusers of the device, but if the thing using it is the swapper, it can't kill that, so there's no way it would unmount.
This isn't quite correct, because it is not how it works on the N900. When you remove the back cover on the N900, the N900 doesn't unmount the SD card, it removes the block device of the SD card from /dev. It becomes completely inaccessible and it doesn't wait for anything to be unmounted, it is effectively the same as unplugging the card reader as far as the system is concerned. And just to be sure I was correct, I temporarily moved my swap to my SD card, turned off the internal swap and took off the back cover, then it crashed and turned itself off.
 

The Following 3 Users Say Thank You to retsaw For This Useful Post:
festivalnut is offline festivalnut
2011-01-19 , 19:51
Posts: 889 | Thanked: 537 times | Joined on Mar 2010 @ scotland
#26
Originally Posted by retsaw View Post
.... And just to be sure I was correct, I temporarily moved my swap to my SD card, turned off the internal swap and took off the back cover, then it crashed and turned itself off.
lmfao! i heard stabbing urself in the eye increases swap speed 3000% !!! jk, dont!
__________________
sarcasm may be the lowest form of wit, but its the only wit i have.

its a sad day when i can't slip at least one hitchhiker reference in somewhere.
 

The Following User Says Thank You to festivalnut For This Useful Post:
Raif is offline Raif
2011-01-19 , 20:04
Posts: 94 | Thanked: 61 times | Joined on Feb 2010 @ Shoreham
#27
Originally Posted by festivalnut View Post
lmfao! i heard stabbing urself in the eye increases swap speed 3000% !!! jk, dont!
oooooowwwwwwwwwwwww my eye!!!!!!
 
epitaph is offline epitaph
2011-01-19 , 20:08
Banned | Posts: 358 | Thanked: 160 times | Joined on Dec 2010
#28
Originally Posted by retsaw View Post
This isn't quite correct, because it is not how it works on the N900. When you remove the back cover on the N900, the N900 doesn't unmount the SD card, it removes the block device of the SD card from /dev. It becomes completely inaccessible and it doesn't wait for anything to be unmounted, it is effectively the same as unplugging the card reader as far as the system is concerned. And just to be sure I was correct, I temporarily moved my swap to my SD card, turned off the internal swap and took off the back cover, then it crashed and turned itself off.
But this isn't discussed here! If u think the increase of speed is placebo i can mean that is ur personal opinion. The fact that dl to a eMMC is almost not bearable tells me that there is a seriuos bottlneck in either the code, the design of the device or both. But as the average joe here is impossible to count to 4 it is hard to explain.
 
retsaw is offline retsaw
2011-01-19 , 20:28
Posts: 701 | Thanked: 585 times | Joined on Sep 2010 @ London, England
#29
Originally Posted by festivalnut View Post
lmfao! i heard stabbing urself in the eye increases swap speed 3000% !!! jk, dont!
Not quite the same, and if I had a spare eye lying around that I could pop in to replace the stabbed one, maybe I'd just do it to prove a point.

The thing is, it is a real risk that people doing this should be informed of, and I needed to prove it, at least to my satisfaction. If this happened at the wrong time it could potentially corrupt your filesystem and force a reflash, ok that's the extreme worst case, ext3 is quite resilient so it may be ok without any corrective action, or it may just need a fsck to fix the problem, but there is still that slim chance. And of course if you do this mod, you need to know you can't remove the back cover whilst it is active.
 

The Following User Says Thank You to retsaw For This Useful Post:
retsaw is offline retsaw
2011-01-19 , 20:34
Posts: 701 | Thanked: 585 times | Joined on Sep 2010 @ London, England
#30
Originally Posted by epitaph View Post
But this isn't discussed here! If u think the increase of speed is placebo i can mean that is ur personal opinion. The fact that dl to a eMMC is almost not bearable tells me that there is a seriuos bottlneck in either the code, the design of the device or both. But as the average joe here is impossible to count to 4 it is hard to explain.
I'm confused, was this intended as a response to my comment because I don't see how it relates to what I said.
 
Reply
Page 3 of 5 12 3 45

Tags
imagination, placebo effect, seriously?, stupid, tragic

« Previous Thread | Next Thread »

 
Forum Jump


All times are GMT. The time now is 15:49.

Contact Us - Home - Archive - Top