Superiornost Linuxa

Goran Arandjelovic: Što preskoči pitanje čega si se ti još dotakao na tom tvom Linuxu? Da nisi više od onog koga opominješ da koristi WinXP, a ne Vistu? :)
Svi tvoji "argumenti" u pređašnjim porukama su prilično naduvani, a tako šuplji, a ti i dalje glavom u zid...

Ma da neće na 256MB... ;) Jedino ako imaš usput i swap od 512MB ;)
Aero trči sa 512MB RAM-a i 128MB kapaciteta grafičke...

vladared: Aero se vuce na 512 M i masina uzasno sporo radi, i da, xgl i beryl rade na 256M i nije bitan swap, posto za 10 godina koliko koristim linux ne secam se da je i jedan swapovao nesto strasno. Neverujete... Probajte!

Body Bag: Za ove 4 godine koriscenja linux-a ne secam se da mi je ikad swap bio popunjen vise od 10-ak MB i to sa otvorenih 10 aplikacija,netom i kompajliranjem u pozadini(imao sam prvo 256 pa 512MB RAM-a)

Body Bag: Za ove 4 godine koriscenja linux-a ne secam se da mi je ikad swap bio popunjen vise od 10-ak MB i to sa otvorenih 10 aplikacija,netom i kompajliranjem u pozadini(imao sam prvo 256 pa 512MB RAM-a)

Ivan Dimkovic: A to da 10 modernih 32-bitnih aplikacija + OS ne izazivaju page-faulte na sistemu sa 256/512 MB RAM-a mozes da pricas nekom drugom, ko je jos na nivou osnova racunara, ovde se to smatra blamom ;-)

Ivan Dimkovic: Apatrid,

Onda ces se sigurno sloziti da je neozbiljno porediti Windows i takav Linux koncept - po pitanju swapovanja?

Ja sam sasvim siguran da ni Windows moze da radi sa jako malo page faultova ako na njemu vrtim Vi i kompajler u komandnoj liniji i sl... ;-) Kao sto sam siguran da mora biti dosta page-faultova u Linux sistemu sa 256 MB RAM-a gde trce noviji KDE i OpenOffice sa nekim pozadinskim poslovima tipa kompajliranje ;-)

Kao sto Apatrid rece, jako je dobro ako se koristi swap

Knjigu u sake, Body Bag

Jeff Atwood explains why Vista uses so much memory. "You have to stop thinking of system memory as a resource and start thinking of it as a a cache. Just like the level 1 and level 2 cache on your CPU, system memory is yet another type of high-speed cache that sits between your computer and the disk drive. And the most important rule of cache design is that empty cache memory is wasted cache memory. Empty cache isn't doing you any good. It's expensive, high-speed memory sucking down power for zero benefit. The primary mission in the life of every cache is to populate itself as quickly as possible with the data that's most likely to be needed - and to consistently deliver a high 'hit rate' of needed data retrieved from the cache."

I thought they were already doing this since like NT4

They were, but now it's improved/more intelligent.

Jeff, you need to read "Windows Internals, Fourth Edition". Task Manager in XP is a big fat liar. Windows Vista's Task Manager is not comparable.

The figure quoted as 'available' in XP is the sum of zero, free, standby and modified lists. The 'system cache' figure is the sum of the system cache working set (amount of physical memory used by the file system cache plus the physical memory used by pageable code and data in drivers, plus the kernel's paged pool) and the standby and modified lists. Your screenshot shows the double-counting: Available + System Cache is 1.5 times physical memory!

When a page is taken out of (trimmed from) a working set, it isn't immediately reused. Instead it is put on either the modified (if modified since last written to the page file or memory-mapped file it belongs to) or standby list. Links are kept from the process to the page. If the process then references the page again before it's paged out, it causes a page fault to occur but Windows can satisfy it simply by fixing up the page table entry - this is termed a 'soft fault'.

So how do pages get onto the other lists? Modified pages become standby pages by being written out to disk - a couple of background threads do this, mapped file pages are written after a maximum of five minutes on the list, and all pages start to be written after the modified list reaches 800 pages (about 3MB). Standby pages become free pages as the balance set manager (a thread that wakes up every second) runs, if the free list is too small. Finally, free pages become zero pages as the system zero page thread (runs at priority 0 and therefore only runs when at least one processor is idle) writes zeros to free pages.

When allocating physical memory Windows prefers zero pages for private user-mode page allocations, and free pages for kernel mode or mapped-file page allocations. (The use of zero pages is a security requirement to prevent processes being able to read other processes' data). If the zero page list is exhausted, Windows will use the free list and zero the page on demand; if the free list is exhausted for a free page allocation, it will then use the zero page list. If both lists are exhausted it will then try the standby list - it then needs to unlink the page from its original process at this point - and in the pathological case that that is empty, it has to take a modified page, write it out, unlink it, zero it, and then give it to a process.

This is why these lists exist - Windows has done work when idle to ensure that there is physical memory available on demand.

Speaking of on-demand: when VirtualAlloc is called to allocate memory, no physical memory is actually allocated. The 'commit charge' is simply incremented. It reserves space in the page file to make sure it can't overcommit on memory, but this reservation is a logical one - nothing is written to the page file. Only when a page is touched, and a page fault ensues, does a physical memory page get allocated (and the data loaded from disk if touching a memory-mapped file).

This commit charge is the value actually shown on the 'PF Usage' meter in XP's Task Manager, and in 'Commit Charge' total. 'Limit' is the sum of all page files plus physical memory minus whatever Windows can't page out.

There's no limit to how large the standby list can grow. The file system cache has a limit on its virtual address size of approx 300MB IIRC, but since this is implemented as a working set, pages discarded from the cache go on the standby or modified list! However, if files are opened as sequential scan, they go on the front of those lists, not the end, so are likely to be reused more quickly.

While on the subject of Task Manager, the Process tab's 'Mem Usage' column is actually the process's working set. However, this includes a lot of shared pages from system DLLs, so the sum of 'Mem Usage' normally is significantly larger than physical memory. It's impossible to tell if your program has a memory leak from this column. Switch on the 'VM Size' column (actually process private bytes) to monitor this, although this won't necessarily drop when you free from a heap.

So XP normally has a lot of moderately-recently-referenced data sitting in memory (but not recently enough to keep it in the working set) - well, once the system has been running for a while. The difference is that Vista is actively preloading data that it thinks you might use soon.

Body Bag: Hahahaha-majke mi ovo je sjajno
Pogotovu je dobro po performanse :-)

degojs: Biće smešno kad Štambuk nađe vremena da se javi (pošto svi znamo da cynique drži sliku Russinovicha na zidu :), čisto da pojasni Body Bagu neke stvari na našem :)

@BodyBag:
Opet se prosipaš. Uzmi knjigu u šake kao što ti je Dimković rekao, videćeš da to i drugi ljudi savetuju :)

Cekaj lepo svog MS advokata posto sam ne znas nista pametno da kazes,kad vec isto tvrdis za mene :-)

Kazi nesto svoje za promenu umesto sto citiras druge ko poslednji drveni advokat/dupelizac :-)
Ti si jedan od onih sto upadaju na sluzbeni ulaz :-)

Windows Defender = antivirus
SQL Server = Apache
Nebuloze o Windowsu vezano za swap, keširanje i slično

Ja nista ne znam-smrc :-)