Attachment 619455 Details for Bug 911347

Effect of journal fragmentation on flushing time

fragmented_journal.txt (text/plain), 3.99 KB, created by Bruno Pesavento on 2015-01-13 18:53:37 UTC

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Creator: Bruno Pesavento

Created: 2015-01-13 18:53:37 UTC

Size: 3.99 KB

patch

obsolete

>41.9 MB journal file
>
>linux-a2yg:/var/log/journal/24ccd2cbdb1849188da8a76382271297 # filefrag system@bd3e8ecaf3574789a8738add70b01355-0000000000015e75-00050c3ffe624bc5.journal
>system@bd3e8ecaf3574789a8738add70b01355-0000000000015e75-00050c3ffe624bc5.journal: 5445 extents found
>
>
>
>25.2 journal file
>
>linux-a2yg:/var/log/journal/24ccd2cbdb1849188da8a76382271297 # filefrag system@bd3e8ecaf3574789a8738add70b01355-000000000000e51b-00050b76e7d817bb.journal
>system@bd3e8ecaf3574789a8738add70b01355-000000000000e51b-00050b76e7d817bb.journal: 3489 extents found
>
>
>
>Before defragmenting current system.journal
>
>linux-a2yg:/var/log/journal/24ccd2cbdb1849188da8a76382271297 # filefrag system.journal
>system.journal: 1865 extents found
>
>gen 13 17:24:13 linux-a2yg systemd-journal[362]: Permanent journal is using 140.0M (max allowed 1.0G, trying to leave 1.5G free of 1.5G avai
>gen 13 17:24:20 linux-a2yg systemd-journal[362]: Time spent on flushing to /var is 7.048175s for 1130 entries.
>
>
>After defragmenting current system.journal
>
>linux-a2yg:/var/log/journal/24ccd2cbdb1849188da8a76382271297 # btrfs fi defrag system.journal
>linux-a2yg:/var/log/journal/24ccd2cbdb1849188da8a76382271297 # filefrag system.journal
>system.journal: 94 extents found
>
>gen 13 17:34:40 linux-a2yg systemd-journal[364]: Permanent journal is using 140.0M (max allowed 1.0G, trying to leave 1.5G free of 1.5G avai
>gen 13 17:34:43 linux-a2yg systemd-journal[364]: Time spent on flushing to /var is 3.181470s for 1156 entries.
>
>but just after a boot and few minutes working, the situation is again...
>
>linux-a2yg:/var/log/journal # filefrag 24ccd2cbdb1849188da8a76382271297/system.journal
>24ccd2cbdb1849188da8a76382271297/system.journal: 1645 extents found
>
>a new reboot and...
>
>linux-a2yg:/var/log/journal # filefrag 24ccd2cbdb1849188da8a76382271297/system.journal
>24ccd2cbdb1849188da8a76382271297/system.journal: 1754 extents found
>
>gen 13 17:55:40 linux-a2yg systemd-journal[363]: Permanent journal is using 140.0M (max allowed 1.0G, trying to leave 1.5G free of 1.5G avai
>gen 13 17:55:46 linux-a2yg systemd-journal[363]: Time spent on flushing to /var is 5.711290s for 1160 entries.
>
>
>defragmenting the whole journal dir...
>
>linux-a2yg:/var/log/journal # btrfs fi defragment -r -f -v /var/log/journal/*/*
>/var/log/journal/24ccd2cbdb1849188da8a76382271297/system@88eb1cb9b5444b91b2f2ed266982c0c9-0000000000000001-00050ad69f1038dc.journal
>/var/log/journal/24ccd2cbdb1849188da8a76382271297/system@bd3e8ecaf3574789a8738add70b01355-0000000000000001-00050ae63824e79b.journal
>/var/log/journal/24ccd2cbdb1849188da8a76382271297/system@bd3e8ecaf3574789a8738add70b01355-0000000000007464-00050b225ca01c47.journal
>/var/log/journal/24ccd2cbdb1849188da8a76382271297/system@bd3e8ecaf3574789a8738add70b01355-000000000000e51b-00050b76e7d817bb.journal
>/var/log/journal/24ccd2cbdb1849188da8a76382271297/system@bd3e8ecaf3574789a8738add70b01355-0000000000015e75-00050c3ffe624bc5.journal
>/var/log/journal/24ccd2cbdb1849188da8a76382271297/system.journal
>Btrfs v3.16.2+20141003
>linux-a2yg:/var/log/journal # filefrag 24ccd2cbdb1849188da8a76382271297/system.journal
>24ccd2cbdb1849188da8a76382271297/system.journal: 2 extents found
>
>reboot... and no hope, at least on this tiny test install!
>
>linux-a2yg:/var/log/journal # filefrag 24ccd2cbdb1849188da8a76382271297/system.journal
>24ccd2cbdb1849188da8a76382271297/system.journal: 1624 extents found
>
>gen 13 18:09:13 linux-a2yg systemd-journal[364]: Permanent journal is using 140.0M (max allowed 1.0G, trying to leave 1.5G free of 1.5G avai
>gen 13 18:09:16 linux-a2yg systemd-journal[364]: Time spent on flushing to /var is 2.961356s for 1153 entries.
>
>But system.journal was a full 16.8 MB file at the time of boot, growing to 25.2MB with flushing.
>The last time this happened (with no defragmenting) flushing time was three times as much:
>
>gen 10 20:53:12 linux-a2yg systemd-journal[362]: Permanent journal is using 196.0M (max allowed 400.0M, trying to leave 1.5G free of 1.6G av
>gen 10 20:53:20 linux-a2yg systemd-journal[362]: Time spent on flushing to /var is 8.815520s for 1134 entries.
>
>
>
>

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Attachments on bug 911347: 619347 | 619455 | 619596 | 620725 | 621355