Date: Fri, 16 Jul 2004 15:05:24 +0300 From: Nikos Vassiliadis <nvass@teledome.gr> To: Wojciech Puchar <wojtek@tensor.3miasto.net> Cc: freebsd-questions@freebsd.org Subject: Re: FreeBSD beginner (NetBSD advanced) Message-ID: <200407161505.24937.nvass@teledome.gr> In-Reply-To: <Pine.NEB.4.60.0407161236400.21969@chylonia.3miasto.net> References: <Pine.NEB.4.60.0407152019430.24734@chylonia.3miasto.net> <200407161045.35953.nvass@teledome.gr> <Pine.NEB.4.60.0407161236400.21969@chylonia.3miasto.net>
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> does FreeBSD deallocate pages that are unused. > > NetBSD does not. if you create 100MB file on mfs and delete it, VM size of > mfs is still over 100MB. while it will get swapped out it's a kind of > nonsense IMHO FreeBSD tries to swap out idle pages. That means that you'll have more physical memory available for programs, cacheing, etc. So it's nice:) I am not by any means FreeBSD kernel expert. Not at all expert! There is a vmm description on your new FreeBSD system by Matthew Dillon who has made many improvments to it. /usr/share/doc/en/articles/vm-design Cheers, NikV On Friday 16 July 2004 13:38, Wojciech Puchar wrote: > > I have used a single 256MB mfs on FreeBSD for months without any problem. > > I was not doing heavy IO on it, it was used in a /tmp fashion and most of > > the time was swapped out, going down to 8MB resident size at times. > > does FreeBSD deallocate pages that are unused. > > NetBSD does not. if you create 100MB file on mfs and delete it, VM size of > mfs is still over 100MB. while it will get swapped out it's a kind of > nonsense IMHO > > >> softdeps in NetBSD is very buggy. putting very high load like deleting > >> huge tree or unpacking it easily triggers DDB with ffs_something panic > >> :( > > > > I have the feeling that NetBSD without softdeps performs much better than > > FreeBSD. I can live without them on NetBSD. > > i have too. anyway softdeps is big speedup. > > i tried async and doing sync every 5 seconds. looks good. > > > I think you will miss ALTQ. There is a patch for FreeBSD-4.8 at Kenjiro's > > page. > > i read manual page about ipfw yesterday. i think i will not miss :) > > > NikV > > > > On Friday 16 July 2004 00:50, Wojciech Puchar wrote: > >>> Wojciech Puchar wrote: > >>>> i installed FreeBSD once to do quick performance tests, and at least > >>>> in disk I/O and fair scheduling it's MUCH better (tested 4.10 and > >>>> 5.1). > >>> > >>> It's nice to be welcomed by higher performance when you switch OSes. > >>> :-) > >> > >> while high performance is always cool, stable performance is even more > >> important under load. I mean if i do 5 things it shouldn't slow down 100 > >> times. > >> > >> in NetBSD especially if you start large file copying whole system slows > >> down terribly. not true with FreeBSD. > >> > >> softdeps in NetBSD is very buggy. putting very high load like deleting > >> huge tree or unpacking it easily triggers DDB with ffs_something panic > >> :( > >> > >>>> my questions: > >>>> > >>>> 1) what is Buf and Cache in top exactly? why buf on 96MB machine gets > >>>> to near 20MB and never goes down? it's almost 1/4 of memory size. > >>> > >>> Cache: number of pages used for VM-level disk caching > >>> Buf: number of pages used for BIO-level disk caching > >> > >> can you explain more? (or redirect me to URL about it) > >> > >> is all things double-buffered?!!!!!! it would be lots of memory traffic. > >> > >> > >> BTW is mfs usable and stable in FreeBSD? and does it make real sense? > >> > >> in NetBSD mfs is terribly unstable. especially large mfs disks easily > >> crash things. > >> > >>>> 2) can i compile kernel with -march=pentium,pentium[234] -O2 > >>>> optimization? in NetBSD 2.0 doing -march=pentium produces kernel that > >>>> doesn't boot at all, just resets. > >>> > >>> If you want to tune your system, tweaking the options from GENERIC by > >>> removing at least: > >>> > >>> cpu I386_CPU > >>> cpu I486_CPU > >> > >> did this. > >> > >>> ...will probably result in the greatest improvement, along with > >>> disabling WITNESS and such if using -CURRENT. See "man tuning". > >> > >> oh - i never did it... > >> > >>> Using -march=pentium is likely to be worthwhile (assuming you don't > >>> have a > >> > >> with heavy CPU-bound userland binaries i measured 10-25% gain. > >> > >>> 386 :-), higher than that may run into problems. Higher optimizations > >>> than -O are not supported, although work is underway to fix the > >>> remaining code issues (mainly in libalias used by NAT), as I > >>> understand. > >>> > >>> If you want to try -O2, give it a shot, but you might consider using > >>> either "-Os" rather than "-O2", or try "-O2 -fno-strict-aliasing". > >> > >> why -Os? it makes slower but smaller code? > >> > >> will lower memory traffic/better cache hitting give more gain than it's > >> lost because of slower code. > >> > >>>> 3) how can i disable compiling, using etc.. all that LKM (KLD) stuff? > >>>> > >>>> i really prefer one static kernel. > >>> > >>> Read the handbook on building the kernel. > >> > >> what i missed? > >> > >> i already built a kernel, found how to disable modules but all kld stuff > >> is still compiled in! > >> > >> yes i can just do rm *.ko but removing kld from kernel would be even > >> nicer. > >> > >>>> 4) is IPv6 working well? (i mean no crashes etc...) i will get real > >>>> IPv6 zone allocation soon and want to use it. > >>> > >>> IPv6 seems to work well, yes. > >>> > >>>> 5) what is used in FreeBSD for traffic management. NetBSD has altq - > >>>> please just give me a name i will RTFM. > >>> > >>> If you want to use that, ipf/altq should be available in -CURRENT. > >>> Otherwise, ipfw & dummynet is another choice. > >>> > >>>> 6) how to turn using serial port as console on i386? my home machine > >>>> is headless, i'm using X terminals to access it. > >>> > >>> See the handbook. > >>> > >>>> 7) does FreeBSD support 2 CPUs on i386? > >>> > >>> Sure. See the SMP section of the kernel config file. > >>> > >>>> should i go to 4.10 or better 5.2.1? stability is really important to > >>>> me. > >>> > >>> 4.10, unless there's a feature from -CURRENT that you don't want to > >>> live without. > >> > >> i don't think it is unless 4.10 has: > >> > >> 1) multiCPU > >> 2) traffic shaping > >> 3) nat > >> 4) firewalling > >> 5) IPv6 > >> 6) tun device > >> > >> i don't think i need anything more > >> _______________________________________________ > >> freebsd-questions@freebsd.org mailing list > >> http://lists.freebsd.org/mailman/listinfo/freebsd-questions > >> To unsubscribe, send any mail to > >> "freebsd-questions-unsubscribe@freebsd.org" > > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to > "freebsd-questions-unsubscribe@freebsd.org"
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