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Message-ID: <3A4911ED.95A73903@dm.ultramaster.com>
Date: Tue, 26 Dec 2000 16:47:25 -0500
From: David Mansfield <lkml@dm.ultramaster.com>
Organization: Ultramaster Group LLC
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To: Jens Axboe <axboe@suse.de>, lkml <linux-kernel@vger.kernel.org>
Subject: Re: cdrom changes in test13-pre2 slow down cdrom access by 70%
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> > >
> > > The cdrom changes that went into test13-pre2 really kill the performance
> > > of my cdrom.  I'm using cdparanoia to read audio data, and it normally

... cut ...

> Anyway, do you think a 'try to allocate 8, if that fails, try to
> allocate 1' solution would be a simple compromise?  That should be easy
> to do, based on the above code (if kmalloc returns NULL && frames > 1,
> frames = 1, retry...).
> 

Jens, 

Here's a version of the above idea, ontop of the patch you sent.  It's
cut and pasted, but I don't think it's whitespace mangled...  I haven't
actually run with this patch, but it does compile :-)

--- drivers/cdrom//cdrom.c	2000/12/26 17:53:14	1.6.4.2
+++ drivers/cdrom//cdrom.c	2000/12/26 21:39:42
@@ -2004,8 +2004,15 @@
 
 		frames = ra.nframes > 8 ? 8 : ra.nframes;
 
-		if ((cgc.buffer = (char *) kmalloc(CD_FRAMESIZE_RAW * frames,
GFP_KERNEL)) == NULL)
-			return -ENOMEM;
+	retry:
+		if ((cgc.buffer = (char *) kmalloc(CD_FRAMESIZE_RAW * frames,
GFP_KERNEL)) == NULL) {
+			if (frames > 1) {
+				frames = 1;
+				goto retry;
+			} else {
+				return -ENOMEM;
+			}
+		}
 
 		if (!access_ok(VERIFY_WRITE, ra.buf, ra.nframes*CD_FRAMESIZE_RAW)) {
 			kfree(cgc.buffer);

David


-- 
David Mansfield                                           (718) 963-2020
david@ultramaster.com
Ultramaster Group, LLC                               www.ultramaster.com
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