Updated patch to the LZ4 metadata compression http://cr.illumos.org/~webrev/DKOIman/LZ4_MD/ ZDB output is attached. Not so big gain on compression rate, though, it is better. Also, it was shown in initial lz4 commit that lz4 is faster. That's why changing metadata compression to the lz4 aglorithm is a reasonable idea. --Daniil Lunev.
On Wed, Jun 11, 2014 at 9:46 AM, Matthew Ahrens <[email protected]> wrote: > resend to [email protected], where an alternate patch was posted. > > --matt > > > On Tue, Jun 10, 2014 at 7:23 PM, Matthew Ahrens <[email protected]> > wrote: > >> This looks generally good, but I'm concerned about enabling the feature >> from this code path. I think it will work, but it doesn't really have the >> right locks to ensure that it will continue to work. I think >> dmu_write_policy() should just check if the property is already active. We >> could add a separate routine to ensure that lz4 is always active. >> Specifically: >> >> 1. Register the LZ4_COMPRESS feature with >> zfeature_register(activate_on_enable==B_TRUE). >> 2. To deal with pools that already have the feature enabled but not >> active, activate the feature if it is enabled but not yet active. >> spa_sync_upgrades() would be an appropriate place to do this. >> 3. Don't bother activating the feature when doing "zfs set >> compression=lz4" (i.e. remove the ZFS_PROP_COMPRESSION case from >> zfs_prop_set_special(); remove zfs_prop_activate_feature{_sync,_check}) >> 4. Update the zpool-features.5 manpage to indicate that the feature will >> be activated when enabled. See the documentation of the birth_hole feature >> for example wording to copy. >> >> --matt >> >> >> On Tue, Jun 10, 2014 at 12:34 PM, Daniil Lunev via illumos-developer < >> [email protected]> wrote: >> >>> Hello, all. >>> As the lz4 algorithm is better than other we have in illumos. Though, we >>> still use lzjb to compress metadata. Here is the patch to use lz4 for the >>> metadata when the corresponing feature is enabled. >>> http://cr.illumos.org/~webrev/DKOIman/LZ4_MD/ Mail_msg is attached, >>> Thanks, >>> Daniil Lunev >>> P.S. Sorry if it's duplicate - somehow first mail didn't go. >>> *illumos-developer* | Archives >>> <https://www.listbox.com/member/archive/182179/=now> >>> <https://www.listbox.com/member/archive/rss/182179/21175174-cd73734d> | >>> Modify >>> <https://www.listbox.com/member/?member_id=21175174&id_secret=21175174-792643f6> >>> Your Subscription <http://www.listbox.com> >>> >> >> >
zdb_lz4.test
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zdb_lz4_4k.test
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zdb_none.test
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zdb_none_4k.test
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