io_tester: implement unlinking via blocks discarding #2141
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Experimentation can be done with fio, it's just playing with configuration files. |
This change is intended to implement a possibility
to select the implementation of unlink operation
used by unlink_request_type.
A new YAML parameter called 'unlink_type' is now
available to the users. Two following values are supported:
a) ordinary - uses unlink() to remove a file
b) blocks_discarding - opens a file, unlinks it, then
issues trim request for each block
according to RPS parameter. In the
end closes the file.
It will be used to conduct measurements related to
impact of unlinking on read and write operations.
Signed-off-by: Patryk Wrobel <patryk.wrobel@scylladb.com>
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pwrobelse
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Jun 5, 2024
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| future<size_t> issue_blocks_discarding_unlink() { | ||
| return ensure_file_to_discard_open().then([this]() { | ||
| return discard_next_block(); | ||
| }).then([this]() { | ||
| return close_file_if_all_blocks_discarded(); | ||
| }).then([]() { | ||
| return make_ready_future<size_t>(0u); | ||
| }); | ||
| } |
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Sadly, the behavior of these lines of code differs from the behavior of fallocate --punch-hole tool.
When the workload is inspected via blktrace, the trim requests are issued only after the flush completes via xfsaild.
I also tested calling unlink() when all blocks are discarded. No difference.
When I added a call to fsync() after each discard is issued, then I saw trim requests issued with certain frequency.
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This change is intended to implement a possibility
to select the implementation of unlink operation
used by unlink_request_type.
A new YAML parameter called 'unlink_type' is now
available to the users. Two following values are supported:
a) ordinary - uses unlink() to remove a file
b) blocks_discarding - opens a file, unlinks it, then
issues trim request for each block
according to RPS parameter. In the
end closes the file.
It will be used to conduct measurements related to
impact of unlinking on read and write operations.