phunni Posted April 23, 2003 Report Share Posted April 23, 2003 I read somewhere on this site (I can't find the post - just didd a search for it) where someone was asking about how much memory the Linux kernel could handle. The thread seemed to be suggesting that over a certaim amount of memory (256 or something like that) all memeory was imply used for caching - is this true? I must admit that this sounds a bit odd - so I hope someone is going to correct me. I do see that caching wouldbe very useful in restarting apps - but it also seems to me that running apps may be very memory hungry too Quote Link to comment Share on other sites More sharing options...
tyme Posted April 23, 2003 Report Share Posted April 23, 2003 I'm thinking you may have misread it, but I could be wrong. If I remember from the discussions I've read on linux memory management, it _does_ do chaching, but I don't take it takes everything over 256mb. I could be way off base, though Quote Link to comment Share on other sites More sharing options...
Relic2K Posted April 23, 2003 Report Share Posted April 23, 2003 I read somewhere on this site (I can't find the post - just didd a search for it) where someone was asking about how much memory the Linux kernel could handle. The thread seemed to be suggesting that over a certaim amount of memory (256 or something like that) all memeory was imply used for caching - is this true? I must admit that this sounds a bit odd - so I hope someone is going to correct me. I do see that caching wouldbe very useful in restarting apps - but it also seems to me that running apps may be very memory hungry too Not exactly clear on the question, but linux should be able to handle any and as much memory as you can cram into your motherboard, and as much swap as you care to create. Linux/Unix is much better at managing memory than Windows is. Quote Link to comment Share on other sites More sharing options...
johnnyv Posted April 23, 2003 Report Share Posted April 23, 2003 well i have 768mb, the normal kernel only handles up to 8XX mb, the enterprise handle lots more. I don't use any swap with just some mozilla windows open and a terminal [john@bob john]$ free total used free shared buffers cached Mem: 773452 398004 375448 0 23696 265048 -/+ buffers/cache: 109260 664192 Swap: 425680 0 425680 [john@bob john]$ here i have ten tabs open in mozilla open office writer the gimp another terminal running counter-strike via wine in a 1024 X 768 window & getting 70fps And still no swap [john@bob john]$ free total used free shared buffers cached Mem: 773452 682616 90836 0 27400 393700 -/+ buffers/cache: 261516 511936 Swap: 425680 0 425680 [john@bob john]$ I am using the enterprise kernel btw, will soon increase my ram to 1024mb so will need it then Quote Link to comment Share on other sites More sharing options...
Michel Posted April 23, 2003 Report Share Posted April 23, 2003 I don't like to be dependent on Mandrake-kernels(ALthough I've "only" 128 MB of Ran, so no probs dor me:)). Isn't there a patch you could apply to the kernel to make it possible to handle over 8xx MB of Ram....It's nice that Mandrake makes the kernels...but I want to be able to make the best possible kernel for my computer(Maybe something I want to test out in the future when I've lots of time :)). Quote Link to comment Share on other sites More sharing options...
aru Posted April 23, 2003 Report Share Posted April 23, 2003 You don't need to apply any special patch, just select the option "Processor type and features --> High Memory Support" when configuring and then recompile the kernel High Memory support CONFIG_NOHIGHMEM Linux can use up to 64 Gigabytes of physical memory on x86 systems. However, the address space of 32-bit x86 processors is only 4 Gigabytes large. That means that, if you have a large amount of physical memory, not all of it can be "permanently mapped" by the kernel. The physical memory that's not permanently mapped is called "high memory". If you are compiling a kernel which will never run on a machine with more than 960 megabytes of total physical RAM, answer "off" here (default choice and suitable for most users). This will result in a "3GB/1GB" split: 3GB are mapped so that each process sees a 3GB virtual memory space and the remaining part of the 4GB virtual memory space is used by the kernel to permanently map as much physical memory as possible. If the machine has between 1 and 4 Gigabytes physical RAM, then answer "4GB" here. If more than 4 Gigabytes is used then answer "64GB" here. This selection turns Intel PAE (Physical Address Extension) mode on. PAE implements 3-level paging on IA32 processors. PAE is fully supported by Linux, PAE mode is implemented on all recent Intel processors (Pentium Pro and better). NOTE: If you say "64GB" here, then the kernel will not boot on CPUs that don't support PAE! The actual amount of total physical memory will either be auto detected or can be forced by using a kernel command line option such as "mem=256M". (Try "man bootparam" or see the documentation of your boot loader (grub, lilo or loadlin) about how to pass options to the kernel at boot time.) If unsure, say "off". 4GB CONFIG_HIGHMEM4G Select this if you have a 32-bit processor and between 1 and 4 gigabytes of physical RAM. 64GB CONFIG_HIGHMEM64G Select this if you have a 32-bit processor and more than 4 gigabytes of physical RAM. Quote Link to comment Share on other sites More sharing options...
qnr Posted April 23, 2003 Report Share Posted April 23, 2003 I'm using high memory, this shows what I have, and how it was being used at boot: terry@timestorm: /home/terry 08:58:30 $ free -t total used free shared buffers cached Mem: 1032916 1016676 16240 0 163584 528800 -/+ buffers/cache: 324292 708624 Swap: 1959920 17032 1942888 Total: 2992836 1033708 1959128 dmesg Linux version 2.4.21-pre5-ac3 (root@timestorm.ross.com) (gcc version 3.2.1) #1 Tue Apr 22 15:46:36 PDT 2003 BIOS-provided physical RAM map: BIOS-e820: 0000000000000000 - 000000000009fc00 (usable) BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved) BIOS-e820: 00000000000f0000 - 0000000000100000 (reserved) BIOS-e820: 0000000000100000 - 000000003fff0000 (usable) BIOS-e820: 000000003fff0000 - 000000003fff3000 (ACPI NVS) BIOS-e820: 000000003fff3000 - 0000000040000000 (ACPI data) BIOS-e820: 00000000ffff0000 - 0000000100000000 (reserved) 127MB HIGHMEM available. 896MB LOWMEM available. On node 0 totalpages: 262128 zone(0): 4096 pages. zone(1): 225280 pages. zone(2): 32752 pages. Kernel command line: auto BOOT_IMAGE=linux-2.4.21 ro root=303 devfs=nomount vga=ask ide0=ata66 ide1=ata66 idebus=66 ide_setup: ide0=ata66 ide_setup: ide1=ata66 ide_setup: idebus=66 Local APIC disabled by BIOS -- reenabling. Found and enabled local APIC! Initializing CPU#0 Detected 1199.998 MHz processor. Console: colour VGA+ 80x25 Calibrating delay loop... 2392.06 BogoMIPS Memory: 1032760k/1048512k available (1937k kernel code, 15364k reserved, 654k data, 156k init, 131008k highmem) Dentry cache hash table entries: 131072 (order: 8, 1048576 bytes) Inode cache hash table entries: 65536 (order: 7, 524288 bytes) Mount cache hash table entries: 512 (order: 0, 4096 bytes) Buffer cache hash table entries: 65536 (order: 6, 262144 bytes) Page-cache hash table entries: 262144 (order: 8, 1048576 bytes) Quote Link to comment Share on other sites More sharing options...
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