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aratis
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PostPosted: Mon Sep 13, 2004 10:02 pm    Post subject: 1GB of memory but only 885 being seen? Reply with quote

I am not sure if this is the correct place to post this. Sorry if it is not.

I searched forums briefly but didn't find an answer.

I thought i had my installation done right, unfortunately using the kde system monitor, I am seeeing my memory usage out of the total of 885M, rather than 1G amount physical memory installed. The torsmo monitor displays out of this total as well. My swap partition is also not showing up in these monitors as either 1024 M or 2048 (can't remmeber what i set it at unfortunately as fdisk only reports sizes to me in blocks)


How can i check to make sure that all my memory is being used? This is more of a for future reference thing as i'm going to keep my current install awhile till i get everything the way i want then redo everythign right hopefully on a new install.

I would appreciate any advice or insight into this matter. Thanks for reading.
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hw-tph
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PostPosted: Mon Sep 13, 2004 10:04 pm    Post subject: Reply with quote

You need to enable himem in your kernel configuration. Set it to 4GB and you should be OK.


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Maedhros
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PostPosted: Mon Sep 13, 2004 10:18 pm    Post subject: Reply with quote

Try free -m. That ought to tell you definitively how much RAM and swap space your system knows about.
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aratis
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PostPosted: Mon Sep 13, 2004 10:23 pm    Post subject: Reply with quote

thanks, I will note that for reference :)

As to the swap reporting incorrectly i think i may have figurd that out.

Command (m for help): p

Disk /dev/hda: 60.0 GB, 60000000000 bytes
255 heads, 63 sectors/track, 7294 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/hda1 * 1 2550 20482843+ 7 HPFS/NTFS
/dev/hda2 2551 2555 40162+ 83 Linux
/dev/hda3 2556 2680 1004062+ 82 Linux swap
/dev/hda4 2681 7294 37061955 83 Linux

Command (m for help):

assuming 512 B blocks:
1004062 / 512 = 1961. blah / 2 = 980. blah (981 is the swap total being shown in system monitors with no decimal places so that is correct)
1004062 / 1000 = 1004. blah this would seem to be close to 1000M. I wonder if when you specify file system sizes they are using standard SI stuff rather than base 2 calculations. The whole MiB vs MB thing.
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d_adams
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PostPosted: Tue Sep 14, 2004 12:01 am    Post subject: Reply with quote

You could always just open a terminal and type in "top" at the prompt, and gives you current statistics of your pc. Shows cpu use, memory use and swap use, along with pids for every process running.
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aratis
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PostPosted: Tue Sep 14, 2004 1:14 am    Post subject: Reply with quote

ok, top, and free both agree that i am indeed only seeing a portion(most of it) of the total memory.

I googled around for the himem option, and read taht is could cause slowdowns.. Any experience with this?


Thanks.
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KingTaco
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PostPosted: Tue Sep 14, 2004 1:35 am    Post subject: Reply with quote

aratis wrote:
ok, top, and free both agree that i am indeed only seeing a portion(most of it) of the total memory.

I googled around for the himem option, and read taht is could cause slowdowns.. Any experience with this?


Thanks.


You have 3 options in your kernel: off, 4GB, 64GB

off implys a limit of ~896MB. there is no disearnable speed difference between off & 4. the reason(according to kernel maintainers) that it defaults to off is to support some really old machines. IMHO, this should be changed to 4GB, but thats up to the kernel ppl. anyway, 64GB is slower than the the others due to the way that i386+ procs access memory. in the 2 smaller sizes, there are 2 references to the GDT(This is a table that maps physical addresses to logical ones, present in every 32bit OS That I know of), however with 64GB it references 3 times. note that(I think) the processor can sometimes optimize away 1 of the 3 calls, but not all the time. So the end result is you have 60GB more ram(and process address space, I think) available, however you will run a bit slower. If my memory serves me correctly, I think it's a slowdown in memory accesses buy 10-20%
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aratis
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PostPosted: Tue Sep 14, 2004 6:05 am    Post subject: Reply with quote

I have learned alot, thank you alll for your time and informative responses!
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PrakashP
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PostPosted: Tue Sep 14, 2004 6:17 am    Post subject: Reply with quote

If you want 1GB LOWMEM, try this. No highmem needed, thus better performance. I think this patch is from Con Kolivas.

Code:

Index: linux-2.6.8-rc2-mm2/arch/i386/kernel/vmlinux.lds.S
===================================================================
--- linux-2.6.8-rc2-mm2.orig/arch/i386/kernel/vmlinux.lds.S   2004-05-23 12:54:46.000000000 +1000
+++ linux-2.6.8-rc2-mm2/arch/i386/kernel/vmlinux.lds.S   2004-08-04 00:20:02.219462913 +1000
@@ -11,7 +11,7 @@
 jiffies = jiffies_64;
 SECTIONS
 {
-  . = 0xC0000000 + 0x100000;
+  . = 0xB0000000 + 0x100000;
   /* read-only */
   _text = .;         /* Text and read-only data */
   .text : {
Index: linux-2.6.8-rc2-mm2/include/asm-i386/page.h
===================================================================
--- linux-2.6.8-rc2-mm2.orig/include/asm-i386/page.h   2004-08-03 01:29:28.000000000 +1000
+++ linux-2.6.8-rc2-mm2/include/asm-i386/page.h   2004-08-03 23:58:16.000000000 +1000
@@ -123,9 +123,9 @@
 #endif /* __ASSEMBLY__ */
 
 #ifdef __ASSEMBLY__
-#define __PAGE_OFFSET      (0xC0000000)
+#define __PAGE_OFFSET      (0xB0000000)
 #else
-#define __PAGE_OFFSET      (0xC0000000UL)
+#define __PAGE_OFFSET      (0xB0000000UL)
 #endif
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gnychis
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PostPosted: Wed Sep 07, 2005 1:47 am    Post subject: Reply with quote

how do you apply this patch? is there somewhere i can look for instructions?

thanks!
George
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sparks
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PostPosted: Wed Sep 07, 2005 10:10 pm    Post subject: Reply with quote

I asked a similar question a while back, here: "should I enable highmem?" The thread is pretty old, Feb of '04, but still has some good advice.
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Deathwing00
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PostPosted: Thu Sep 08, 2005 11:24 am    Post subject: Reply with quote

Moved from Installing Gentoo to Duplicate Threads in favor of https://forums.gentoo.org/viewtopic-t-132937.html
Please, follow up that thread.
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