Messages in this thread | | | Date | Tue, 2 Nov 1999 23:50:10 +0100 (MET) | From | Gerard Roudier <> | Subject | Re: Linux Buffer Cache Does Not Support Mirroring |
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On Tue, 2 Nov 1999, Jeff V. Merkey wrote:
> Gerard, > > The Statement relates to increased parallelism on FS code paths (they > don't have to block), and allows multiple I/O requests to be handled as > a "bundle" rather than one at a time. The benefit is immediately > obvious since less time is spent calling semaphore and sync code in the > kernel (shorter code paths, less rendudant calling of sync code). There > are also benefits for remirroring since disk reqests can now be > coalesced into runs and ordered based on block number for elevator > seeking. Understand now?
I have reread your previous mail and I had rather to guess than to understand what you meant.
As you know, UNIX systems basically implement synchronous IO (wait for completion), asynchronous IO (write and don't care) and deferred IO (buffer cache). I have been very frustrated in the past when switching from VMS to UNIX. I knew for 7 years working on VMS applications the vertue of completion callbacks called ASTs on VMS and am currently maintaining SCSI drivers that rely on hardware interrupts.
As you can see I have nothing to understand now from you. I just will stop considering your postings given your agressivity and your evil way to shit on everything that is not what you used to working on in your pre-free-software life.
Bye, Gérard.
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