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307292 |
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14-Oct-2016 |
mav |
MFC r305340: MFC r305337: 7004 dmu_tx_hold_zap() does dnode_hold() 7x on same object
Using a benchmark which has 32 threads creating 2 million files in the same directory, on a machine with 16 CPU cores, I observed poor performance. I noticed that dmu_tx_hold_zap() was using about 30% of all CPU, and doing dnode_hold() 7 times on the same object (the ZAP object that is being held).
dmu_tx_hold_zap() keeps a hold on the dnode_t the entire time it is running, in dmu_tx_hold_t:txh_dnode, so it would be nice to use the dnode_t that we already have in hand, rather than repeatedly calling dnode_hold(). To do this, we need to pass the dnode_t down through all the intermediate calls that dmu_tx_hold_zap() makes, making these routines take the dnode_t* rather than an objset_t* and a uint64_t object number. In particular, the following routines will need to have analogous *_by_dnode() variants created:
dmu_buf_hold_noread() dmu_buf_hold() zap_lookup() zap_lookup_norm() zap_count_write() zap_lockdir() zap_count_write()
This can improve performance on the benchmark described above by 100%, from 30,000 file creations per second to 60,000. (This improvement is on top of that provided by working around the object allocation issue. Peak performance of ~90,000 creations per second was observed with 8 CPUs; adding CPUs past that decreased performance due to lock contention.) The CPU used by dmu_tx_hold_zap() was reduced by 88%, from 340 CPU-seconds to 40 CPU-seconds.
Sponsored by: Intel Corp.
Closes #109
Reviewed by: Steve Gonczi <steve.gonczi@delphix.com> Reviewed by: George Wilson <george.wilson@delphix.com> Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com> Reviewed by: Ned Bass <bass6@llnl.gov> Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov> Author: Matthew Ahrens <mahrens@delphix.com>
openzfs/openzfs@d3e523d489a169ab36f9ec1b2a111a60a5563a9f
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#
307122 |
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11-Oct-2016 |
mav |
MFC r305209: MFV r302660: 6314 buffer overflow in dsl_dataset_name
illumos/illumos-gate@9adfa60d484ce2435f5af77cc99dcd4e692b6660 https://github.com/illumos/illumos-gate/commit/9adfa60d484ce2435f5af77cc99dcd4e6 92b6660
https://www.illumos.org/issues/6314 Callers of dsl_dataset_name pass a buffer of size ZFS_MAXNAMELEN, but dsl_dataset_name copies the datasets' name PLUS the snapshot name to it, resulting in a max of 2 * ZFS_MAXNAMELEN + '@'.
Reviewed by: George Wilson <george.wilson@delphix.com> Reviewed by: Prakash Surya <prakash.surya@delphix.com> Reviewed by: Igor Kozhukhov <ikozhukhov@gmail.com> Approved by: Dan McDonald <danmcd@omniti.com> Author: Matthew Ahrens <mahrens@delphix.com>
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