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Пишет LWN.net (![[info]](http://lj.rossia.org/img/syndicated.gif){kind=small} syn_lwnheadline)@ 2013-08-28 17:27:00 |
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Desmond: Out-Tridging Tridge
Barney Desmond talks
about an rsync performance problem and its solution; the result is an
interesting overview of how rsync works. "Most of the activity in
this MySQL data file occurs at the end, where more zeroes had been written
on the sender’s side. rsync hits this section of the file and is
calculating the rolling checksums as normal. For each checksum, it’s
referring to the hash table, hitting the all-zeroes chain, then furiously
traversing the chain skipping over unusable chunks. Things are now possibly
hundreds of times slower than normal, and the backup job has been running
for over a week with no sign of finishing any time soon; not
sustainable."
Barney Desmond talks
about an rsync performance problem and its solution; the result is an
interesting overview of how rsync works. "Most of the activity in
this MySQL data file occurs at the end, where more zeroes had been written
on the sender’s side. rsync hits this section of the file and is
calculating the rolling checksums as normal. For each checksum, it’s
referring to the hash table, hitting the all-zeroes chain, then furiously
traversing the chain skipping over unusable chunks. Things are now possibly
hundreds of times slower than normal, and the backup job has been running
for over a week with no sign of finishing any time soon; not
sustainable."
