Re: kernel page size explanation
On 7/25/05, Nix <[EMAIL PROTECTED]> wrote: > On Mon, 25 Jul 2005, VASM wrote: > > i had one question > > does the linux kernel support only one default page size even if the > > processor on which it is working supports multiple ? > > No. Some architectures have compile-time support for multiple different > page sizes (e.g. Itanium, SPARC64); many have support for a > (non-swappable) `large pages) system, and a filesystem backed by huge > pages. (Often, the kernel is stored in huge pages, to keep the number > of page table entries wasted by the nonswappable kernel to a minimum.) > > What is *not* presently supported is using multiple page sizes to > back userspace processes; that size is currently fixed at compile-time, > even on architectures supporting multiple variably-sized pages. > are there any specific reasons for not using large page size for userspace processes > -- > `But of course, GR is the very best relativity for the masses.' > --- Wayne Throop > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: kernel page size explanation
On 7/25/05, Nix [EMAIL PROTECTED] wrote: On Mon, 25 Jul 2005, VASM wrote: i had one question does the linux kernel support only one default page size even if the processor on which it is working supports multiple ? No. Some architectures have compile-time support for multiple different page sizes (e.g. Itanium, SPARC64); many have support for a (non-swappable) `large pages) system, and a filesystem backed by huge pages. (Often, the kernel is stored in huge pages, to keep the number of page table entries wasted by the nonswappable kernel to a minimum.) What is *not* presently supported is using multiple page sizes to back userspace processes; that size is currently fixed at compile-time, even on architectures supporting multiple variably-sized pages. are there any specific reasons for not using large page size for userspace processes -- `But of course, GR is the very best relativity for the masses.' --- Wayne Throop - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: kernel page size explanation
i had one question does the linux kernel support only one default page size even if the processor on which it is working supports multiple ? On 7/25/05, Nix <[EMAIL PROTECTED]> wrote: > On 22 Jul 2005, Jesper Juhl suggested tentatively: > > You can > > A) look in the .config file for your current kernel (if your arch > > supports different page sizes at all). > > B) You can use the getpagesize(2) syscall at runtime. getpagesize() > > returns the nr of bytes in a page - man getpagesize - I'm not sure > > that's universally supported though. > > C) You can look at /proc/cpuinfo or /proc/meminfo , IIRC some archs > > report page size there - not quite sure, can't remember... > > D) getconf PAGE_SIZE should work, although what it does on arches > with variable page sizes isn't clear to me. > > -- > `But of course, GR is the very best relativity for the masses.' > --- Wayne Throop > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to [EMAIL PROTECTED] > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: kernel page size explanation
i had one question does the linux kernel support only one default page size even if the processor on which it is working supports multiple ? On 7/25/05, Nix [EMAIL PROTECTED] wrote: On 22 Jul 2005, Jesper Juhl suggested tentatively: You can A) look in the .config file for your current kernel (if your arch supports different page sizes at all). B) You can use the getpagesize(2) syscall at runtime. getpagesize() returns the nr of bytes in a page - man getpagesize - I'm not sure that's universally supported though. C) You can look at /proc/cpuinfo or /proc/meminfo , IIRC some archs report page size there - not quite sure, can't remember... D) getconf PAGE_SIZE should work, although what it does on arches with variable page sizes isn't clear to me. -- `But of course, GR is the very best relativity for the masses.' --- Wayne Throop - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
