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Aug
9
comment Why do damaged hard drives freeze the entire system?
Using an external USB enclosure should help, since you are no longer tieing the faulty disk to your system SATA controller (also, adding an extra layer of sacrificable hardware between your motherboard and a faulty disk is always a good idea).
Jul
7
comment Why are there no odd Windows process Ids?
@Mehrdad: well, USER and GDI handles aren't normally called "kernel" handles (although they are generated by components running in so-called kernel mode).
Jul
6
comment Why are there no odd Windows process Ids?
@BlueRaja: kernel handles are multiple of four and that's contractual, so you can rely on it; process ids (which are not the same as process handles), instead, happen to be multiple of four, but that's just an implementation detail, so you shouldn't rely on it.
Apr
15
awarded  Citizen Patrol
Dec
5
comment How to: Unlimited Bash/shell history?
Warning: this causes headaches with gdb; if you set an HISTSIZE variable it will take it as a 0, thus disabling history size entirely.
Sep
24
awarded  Autobiographer
Aug
31
comment Does every OS need RAM?
(OTOH, in theory you could exploit other RAM (e.g. video RAM) or peripherals mapped in the physical address space)
Aug
31
comment Does every OS need RAM?
In practice it is possible to run a machine with somewhat defective RAM (say, there's just one bank which does not work correctly). If the BIOS doesn't notice (or, if it does notice, there may be the usual F1 override) you can still run an OS like Linux with the BadMEM/BadRAM patch, that instructs the kernel to avoid the specified memory blocks.
Aug
31
comment Does every OS need RAM?
All these arguments about using the processor cache are of dubious validity, since, at least on x86, the cache is not a memory you can access directly. Your code always refers to RAM, but the processor automatically manages its caches so that it doesn't actually have to fetch the data in RAM for most frequently accessed data. But again, there's no assembly instruction to say "store this in cache" "write this in cache", there are registers and there is main memory (with all its weird accessing modes), period.
Aug
15
comment Why doesn't “add more cores” face the same physical limitations as “make the CPU faster”?
Also, in many applications the bottleneck is not the computation time, but the stall time to fetch data from the RAM (or, god forbid it, from disk); so, another major speedup comes from bigger, faster processor caches.
Jul
31
comment How can a 80-bit floating point be used by a 32-bit system?
Well done, +1 :)
Jul
31
comment How can a 80-bit floating point be used by a 32-bit system?
You are failing to mention the most important detail: the x87 FPU on the x86 platform has 80-bit wide floating point registers, so its native calculations are actually done on 80 bits floats, no need to emulate anything in software.
Jul
29
comment Excel VBA program only running at 25% speed
Why would you want to hurt yourself with this madness when you could write your application in a way better language (both VB.NET and C# are arguably better than VBA), that by itself runs faster (JIT-compilation vs interpretation), actually supports concurrency, and still can interact with Excel via the Office PIAs?
May
11
comment Cpu 2 graphs - clarification ?
@DanielB: waiting for a slow disk does not incur in high CPU system time, because the CPU isn't involved at all. Most peripherals use DMA to transfer the data, and the CPU doesn't need to do constant polling anyhow to check if the data is there. If a peripheral is slow to provide the data, the OS scheduler will assign the CPU to something else in the meanwhile (if there's nothing to do the CPU will go to the idle task), and the process waiting for data will be put in wait state (and it won't consume CPU).
May
11
comment Cpu 2 graphs - clarification ?
It's misleading to state that kernel time goes in doing only hardware stuff, and the HAL is only the lowest level of the kernel (actually, it's a small part on which the rest of the kernel rely to abstract some hardware details). The kernel - and, more in general, all the code that runs in kernel mode - does a lot more than that. High kernel time may be associated to polling hardware, heavy IPC usage, heavy calculations performed by code in kernel mode, continuous task switching and a lot more. Here are some tools to analyze kernel CPU usage.
Nov
28
awarded  Necromancer
Nov
23
comment Deleting millions of files
@glglgl: the point is exactly that if you don't want to cause service disruption on the server you have to go slowly, the time where this code sleeps is there to let the server do actually useful work with the disk .
Nov
23
comment Deleting millions of files
The sleep may be a good choice, but nice won't do, since the task here is IO bound, not CPU bound; you may try ionice instead. Notice that if the sleep is too small it will be useless.
Oct
10
awarded  Critic
Oct
10
comment How can a Linux OS be “based on” another Linux OS?
You are confusing the kernel (Linux) with the rest of the software aggregated in distributions.