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Improve performance of large restore commands

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

The testcase that originally took hours now takes 50 seconds.

gdb/
2013-07-29  Anton Blanchard  <anton@samba.org>

	* target.c (memory_xfer_partial): Cap write to 4KB.
This commit is contained in:
Anton Blanchard 2013-11-04 21:39:20 +11:00
parent 88b8e63904
commit 67c059c29e
2 changed files with 11 additions and 0 deletions
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4
gdb/ChangeLog
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@ -1,3 +1,7 @@
2013-11-04 Anton Blanchard <anton@samba.org>
* target.c (memory_xfer_partial): Cap write to 4KB.
2013-11-01 Tiago Stürmer Daitx <tdaitx@linux.vnet.ibm.com>
* breakpoint.c (create_longjmp_master_breakpoint): Allow libc

7
gdb/target.c
View file

@ -1678,6 +1678,13 @@ memory_xfer_partial (struct target_ops *ops, enum target_object object,
void *buf;
struct cleanup *old_chain;
/* A large write request is likely to be partially satisfied
by memory_xfer_partial_1. We will continually malloc
and free a copy of the entire write request for breakpoint
shadow handling even though we only end up writing a small
subset of it. Cap writes to 4KB to mitigate this. */
len = min (4096, len);
buf = xmalloc (len);
old_chain = make_cleanup (xfree, buf);
memcpy (buf, writebuf, len);