Jihad needs scientists
in [Design]
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From: jmfbahciv on 24 Feb 2007 07:31 In article <ermu1l$rph$2(a)blue.rahul.net>, kensmith(a)green.rahul.net (Ken Smith) wrote: >In article <ermmhd$8qk_001(a)s774.apx1.sbo.ma.dialup.rcn.com>, > <jmfbahciv(a)aol.com> wrote: >>In article <erhn0i$em5$4(a)blue.rahul.net>, >> kensmith(a)green.rahul.net (Ken Smith) wrote: >[.....] >>>Sure you can. If the computer is running a printer server, you can >>>predict the right order for the files to be read by the server. If there >>>is a task constantly running to take sliding billion point FFTs, you know >>>what is best for the FFT part. Just because the human may change >>>something it doesn't mean they change everything. >> >>All of this is single-task, single user thinking. > >No, it isn't. It is taking a practical example of a way that real >multiuser systems actually run. I know of plenty OSes and how they actually ran. We even made them go. > It is very common for a small fraction of >the tasks to need the large fraction of the memory. This is just the way >it is in the real world. That all depends on the computer site and who the users are. > >The computer that is doing the work of posting this is a multiuser >machine. It has me on it using only several tens of kilobytes. <GAG> That's too much. > There are >a couple of other users like me and a couple that are doing something that >takes a lot of RAM. > > > >> Computer usage >>by the general population requires more than this. You keep >>looking at the load balance from a naive user POV. > >No, you are just making stuff up because you've been shown to be wrong >about the real world of computers today. Keep thinking like that and you'll never learn something. > >> My biz >>was timesharing from the OS' POV. > >I'm using a company that sells computer time like a timesharing company. >They also sell modem access, and data storage. This is the modern >business model for this sort of company. And that is one business. > > > >>>No, I'm thinking of the case where something very difficult needs to be >>>done with a PC. While it is doing it, the best rules for swapping are >>>known. >> >>Again, I think you are confused about swapping. The OS only needs >>to swap if it has to temporarily delete contents of memory whose >>bit settings have to be restored exactly as they were. > >You only think that because you haven't stopped to think about what I >wrote. We were discussing the case where swapping had to happen. There >is no point in asking at this point if it needs to happen because the >argument has already shown that it must. There is more data to be >maintained than will fit into the RAM of the machine. There is no >question about swapping being needed. The discussion is about the >advantages of having the code specific to the large memory usage make >informed choices about swapping. You are not talking about swapping; you are talking about the working set of pages. You do NOT have to swap code if the storage disk is as fast as the swapping disk. /BAH
From: jmfbahciv on 24 Feb 2007 08:24 In article <ermuqc$rph$3(a)blue.rahul.net>, kensmith(a)green.rahul.net (Ken Smith) wrote: >In article <ermlh8$8ss_012(a)s774.apx1.sbo.ma.dialup.rcn.com>, > <jmfbahciv(a)aol.com> wrote: >>In article <erhnfn$em5$5(a)blue.rahul.net>, >> kensmith(a)green.rahul.net (Ken Smith) wrote: >>>In article <erhd4t$8qk_001(a)s916.apx1.sbo.ma.dialup.rcn.com>, >>> <jmfbahciv(a)aol.com> wrote: >>>>In article <i70nt25k4ubuvllr029cun9ebu1e1bng0a(a)4ax.com>, >>>> MassiveProng <MassiveProng(a)thebarattheendoftheuniverse.org> wrote: >>>>>On Mon, 19 Feb 07 13:29:06 GMT, jmfbahciv(a)aol.com Gave us: >>>>> >>>>>>Not at all. OSes were handling the above problems in the 60s. >>>>>>The reason virtual memory was invented was to solve the above >>>>>>problem. >>>>>> >>>>> The swapping, in this case, CAUSES the interference. >>>> >>>>That has to do with severe memory management problems. >>> >>>No, it is just part of the overhead of doing VM. >> >>Nope. VM doesn't have to swap. Swapping is done to make >>room so a memory request by another task can be serviced. > >You said "nope" and then confirmed that my statement was correct. >Swapping needs to happen if you need more virtual RAM than there is real >RAM. To be able to swap, the code for doing the swapping must always be >in the real RAM. As a result, there is code overhead in having a VM >system. There is also a speed overhead when swapping happens. The OS >uses some amount of CPU time on the taks switching needed to make VM do >the swap. VM isn't swapping. VM allows the OS to manage smaller chunks of memory rather than segments. > > >>I don't know why but people often confuse virtual memory >>addressing with swapping. The two are separate. > >No, you are confused on the issue of needing to swap. No, I'm not. You are. > We have already >discussed why the swapping is needed. In the case we are talking about, >there is more that needs to be in memory than there is physical RAM. You are now talking about two kinds of memory. > > >>> If the speed of >>>results is important, it is better not to have to swap. This means that >>>doing the tasks one after the other is the way to go. >> >>You still have swap if a task is too big for the computer's resources. >>Single-tasking doesn't prevent swapping. It prevents context >>switching, but not swapping. You are confusing context switching >>with swapping. > >No, I am not. The case under discussion was quite specific. There were >two large tasks which individually would fit into physical memory but that >added up to more than would fit. If the two were loaded at the same time, >the results would be later in coming than if you ran them one after the >other. You keep assuming that all the code of both had to be in core even if it wasn't going to executed. > > >>> Back in the day, >>>the IBM370 would "roll out" a program so that it was put on hold while >>>something else was done. >> >>That had to do with resources such as magtape drives, diskpacks, >>etc. > >No it was mostly about RAM. The IBM360 can only address 16M. Running a >copy MVS couldn't get around this hard limit. If there was not enough >address space to fit all the code or data, something had to be rolled out >and processed later. That's why code segments and buffered mode I/O were invented. > > >[....] >>>Windows allocates memory on a least fit basis. This tends to leave a lot >>>of small holes in the memory space. Unfortunately on x86 machines, the >>>memory management doesn't do address translation on a finer grain than the >>>segment size. This leads to a lot of fluff in memory space. >>> >>>Windows doesn't assume that garbage collection is needed nor does it have >>>memory compacting. >> >>By memory compacting, are you talking about shuffling? > >No. In a page based MMU, you don't have this issue. When you only have a >by segment memory management, you end up with gaps in the memory space. >Compacting is a method for gathering the smaller gaps together to make >bigger free blocks. It requires that the data be moved. There are two major methods to do this job: swapping and shuffling. When the swapping device was very slow the last thing picked to do in any memory manager would have been swapping. Shuffling had its own quirks and CATCH-22s. Note that you do not have to swap code if it's reentrant; you can overwrite it in the RAM if the code segment resides on a device whose retrieval speed is equiavlent to memory fetches. OTOH, you do have to preserve data. /BAH
From: jmfbahciv on 24 Feb 2007 08:46 In article <7s2vt2dnen3olpfkhmsue6ui4mssh3p0sn(a)4ax.com>, MassiveProng <MassiveProng(a)thebarattheendoftheuniverse.org> wrote: >On Fri, 23 Feb 07 12:26:21 GMT, jmfbahciv(a)aol.com Gave us: > >> from a naive user POV. > > > Said the twit that reads Usenet and does her "computing" from a dumb >terminal in ASCII. It's my business to watch the computing usage trends. You can't watch the outside of any box if you're penned up inside it. /BAH
From: jmfbahciv on 24 Feb 2007 08:53 In article <ermvfo$rph$5(a)blue.rahul.net>, kensmith(a)green.rahul.net (Ken Smith) wrote: >In article <ermm1f$8qk_001(a)s774.apx1.sbo.ma.dialup.rcn.com>, > <jmfbahciv(a)aol.com> wrote: >>In article <era3ti$tvp$6(a)blue.rahul.net>, >> kensmith(a)green.rahul.net (Ken Smith) wrote: >[.....] >>>> The problem is that the software side >>>>of the biz is dragging its heels and the hardware types are >>>>getting away with not including assists to the OS guys. >>> >>>The most hardware guys have to design hardware to run with Windows. >> >>Sigh! Windows' OS has a grandfather that required those hardware >>assists. Your point is making an excuse for lousy design >>requirements. > >No, I am pointing out what has really happened. Windows was written to >run on the usual DOS hardware. Gradually, features got added until it >needed more stuff than DOS. If I designed a 4096 by 4096 display, I >wouldn't sell very many unless I could make a windows driver for it. > > >[.....] >>>Even just suggesting that there be true backups of peoples machines throws >>>them into a panic. >> >>Good. That's why you should just say the words. That will have >>a ripple effect throughout the industry. > >No, I need my computer to work and be backed up. I don't give the hind >most 3/4 of a rat what happens to the average windows user's data. I know that you don't care. I do care. That is why you don't understand about all kinds of computing usage and I do. > > >>> "Imagine an evil person gets to the PC, deletes all >>>the files of that user and reformats the harddisk on the machine. How >>>long would it take to put it all back as a working system?" has been the >>>question I have asked. >> >>Instead of saying evil person, just say lightning strike or power >>surge or blizzard/hurricane when everything shuts down for 2 weeks. > >That is a lot less damage than an evil person can cause. Backing up by >storing on two computers will serve to protect against lightning. No it won't. There a billions of dollars spent on trying to make one set of computing services non-local. > > >>>>Nope. That won't happen. As soon as you get a procedure and >>>>hard/software/humans in place, MS will change something that >>>>will break it. I've never been able to figure out a independent >>>>way no matter what they did. >>> >>>On just a sinlge PC it is quite easy. >> >>No, it is not. The way files, directories, structures and MOST >>importantly, data has been organized makes it almost impossible >>to manage files on a PC. > >We are talking about a backup. You can just copy the entire hard disk >when it is a single PC. That is not a backup of the files. YOu seem to be talking about a bit-to-bit copy. That will also copy errors which don't exist on the output device. > > >>> Doing the backup of whats on the >>>server is hard. On a single PC, you boot something other than windows and >>>make a bitwise image of the hard disk. When things break, you go back to >>>that other OS and restore the disk as it was. If you have been good about >>>backing up your data files, you don't need to do a full image every day. >> >>That's called an incremental backup. Great care needs to occur >>to combine full and incremental backups. > >No great amount of care is needed. I've done that sort of restore a few >times with no great trouble. Since files are stored with the modification >date, a copy command that checks dates does the hard part. You are very inexperience w.r.t. this computing task. It is not as easy as you make it out to be. Now think about that fact and all the people who are going to be doing all banking online. /BAH
From: Ken Smith on 24 Feb 2007 10:51
In article <erpaqn$8ss_004(a)s934.apx1.sbo.ma.dialup.rcn.com>, <jmfbahciv(a)aol.com> wrote: >In article <ermuv0$rph$4(a)blue.rahul.net>, > kensmith(a)green.rahul.net (Ken Smith) wrote: >>In article <ermmos$8qk_002(a)s774.apx1.sbo.ma.dialup.rcn.com>, >> <jmfbahciv(a)aol.com> wrote: >>[....] >>>>>>I use electronic banking. I go to the banks web site and do it. It is >>>>>>just another "surfing the web" case. I don't have any special software >to >>>>>>do it. I am far from the normal user but even I didn't add anything >>>>>>beyond the web browser to do my banking. >>>>> >>>>>Since you have already converted to on-line banking, why are >>>>>you disputing my statements about it? >>>> >>>>I am disputing your incorrect statements. >>> >>>You cannot know what is incorrect because you've already been >>>herded into doing online banking. >> >>You are completely off your nut on this. > >Not at all. You are already herded into the corral. You will >never experience the pressure that will push the rest into >that pen. It isn't a corral. A corral implies a loss of freedom. I can still write a check or see a teller if I want. I can pay a bill while I'm at work of on vacation. I have lost nothing. -- -- kensmith(a)rahul.net forging knowledge |