Re: read perfomance patchset

[Neil Brown]

On Monday June 19, [EMAIL PROTECTED] wrote:
 Neil hello
 
 if i am not mistaken here:
 
 in first instance of :   if(bi) ...
...
 
 you return without setting to NULL
 

Yes, you are right. Thanks.
And fixing that bug removes the crash.
However

I've been doing a few tests and it is hard to measure much
improvement, which is strange.

I can maybe see a 1% improvement but that could just be noise.
I do some more and see if I can find out what is happening.

Interestingly, with a simple
  dd if=/dev/md1 of=/dev/null bs=1024k
test, 2.6.16 is substantially faster (10%) than 2.6.17-rc6-mm2 before 
that patches are added.  There is something weird there.

Have you done any testing?

NeilBrown
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read perfomance patchset

[Raz Ben-Jehuda(caro)]

Neil hello

if i am not mistaken here:

in first instance of :   if(bi) ...
  ...

you return without setting to NULL

+static struct bio *remove_bio_from_retry(raid5_conf_t *conf)
+{
+   struct bio *bi;
+
+   bi = conf-retry_read_aligned;
+   if (bi) {
--   return bi;
--   conf-retry_read_aligned = NULL;
+   }
+   bi = conf-retry_read_aligned_list;
+   if(bi) {
+   conf-retry_read_aligned = bi-bi_next;
+   bi-bi_next = NULL;
+   bi-bi_phys_segments = 1; /* biased count of active stripes */
+   bi-bi_hw_segments = 0; /* count of processed stripes */
+   }
+
+   return bi;
+}

--
Raz
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