Messages in this thread | | | From | "Jeff Merkey" <> | Subject | Re: Windows NT File Systems and Linux File Systems | Date | Wed, 23 Jun 1999 09:06:34 -0600 |
| |
Steve,
Bless your heart, you missed the point. Most of the stuff in NT is geared towards parallelism, not disk vs. cache access. FYI. Nice to hear from you though. I know I'm in trouble when I get an answer from you.
Your friend,
Jeff
----- Original Message ----- From: Stephen C. Tweedie <sct@redhat.com> To: Jeff Merkey <jmerkey@timpanogas.com> Cc: Ingo Molnar <mingo@chiara.csoma.elte.hu>; <linux-kernel@vger.rutgers.edu>; Stephen Tweedie <sct@redhat.com> Sent: Wednesday, June 23, 1999 8:24 AM Subject: Re: Windows NT File Systems and Linux File Systems
> Hi, > > On Tue, 22 Jun 1999 12:15:13 -0600, "Jeff Merkey" > <jmerkey@timpanogas.com> said: > > > I've reviewed the code sections you are refering to. This is along the same > > lines to what Windows NT is doing, but not identical. From what I've seen, > > this could really help Linux. The next step would be to create file runs > > for SMP read/write. > > We can do that on Linux. The io_request spinlock protects the block > device request structures, but otherwise the actual IO to/from can > progress in parallel on multiple devices and (in 2.3) copies between > user space and the caches can also run in parallel. > > > MS actually stores the file allocations in the VM Cache, and then > > transacts them by completely bypassing the file system driver. In > > essence, the file system driver is reduced to simply being an on-disk > > decode agent for the VM Cache Manager. > > Just like Linux. The "decode agent" for existing data is the bmap() > function. 2.3 now uses a similar fs-supplied agent for writes too, > which encapsulates both overwrite and allocate in a transparent manner. > > > In the Windows NT Fenris, only certain requests ever make it into an > > IORP request. Files are read and written directly by the VM Cache > > Manager and the File System driver only maintains meta-data fior the > > file system (FAT's, Dirs, etc.). This is how NTFS, FASTFAT, CDFS, and > > FENRIS are all structured on Windows NT. WARNING!!!! There are some > > very complex unwind cases associated with the methods used by MS in > > their file systems. On SMP, however, their model is unequalled from > > structly a parallelism standpoint. > > Linux behaves very similarly. Only requests which have to hit disk > actually get a "struct request" generated; everything else is done in > cache. > > --Stephen >
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
| |