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Re: [PATCH] Improve performance of large restore commands


On 07/25/2013 09:08 AM, Anton Blanchard wrote:

I noticed a large (100MB) restore took hours to complete. The problem
is target_xfer_partial repeatedly mallocs and memcpys the entire
100MB buffer only to find a small portion of it is actually written.

We already cap reads to 4K, so do that for writes. The testcase that
originally took hours now takes 50 seconds.

--

2013-07-25  Anton Blanchard  <anton@samba.org>

	* target.c (target_write_with_progress): Cap write to 4K

Index: b/gdb/target.c
===================================================================
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -2287,9 +2287,11 @@ target_write_with_progress (struct targe

    while (xfered < len)
      {
+      /* Cap the write to 4K */
+      int to_transfer = min(4096, len - xfered);
        LONGEST xfer = target_write_partial (ops, object, annex,
  					   (gdb_byte *) buf + xfered,
-					   offset + xfered, len - xfered);
+					   offset + xfered, to_transfer);

        if (xfer == 0)
  	return xfered;



Looks good to me.

Did you consider extending the comment a little to explain what will happen if we don't cap the write to 4K?

Thanks,
Luis


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