Date: Fri, 26 May 2017 12:13:59 +0000 (UTC) From: Andriy Gapon <avg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-vendor@freebsd.org Subject: svn commit: r318947 - vendor-sys/illumos/dist/uts/common/fs/zfs vendor-sys/illumos/dist/uts/common/fs/zfs/sys vendor/illumos/dist/cmd/ztest Message-ID: <201705261213.v4QCDxT5097349@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: avg Date: Fri May 26 12:13:58 2017 New Revision: 318947 URL: https://svnweb.freebsd.org/changeset/base/318947 Log: 7578 Fix/improve some aspects of ZIL writing. illumos/illumos-gate@c5ee46810f82e8a53d2cc5a487568a573f449039 https://github.com/illumos/illumos-gate/commit/c5ee46810f82e8a53d2cc5a487568a573f449039 https://www.illumos.org/issues/7578 After some ZIL changes 6 years ago zil_slog_limit got partially broken due to zl_itx_list_sz not updated when async itx'es upgraded to sync. Actually because of other changes about that time zl_itx_list_sz is not really required to implement the functionality, so this patch removes some unneeded broken code and variables. Original idea of zil_slog_limit was to reduce chance of SLOG abuse by single heavy logger, that increased latency for other (more latency critical) loggers, by pushing heavy log out into the main pool instead of SLOG. Beside huge latency increase for heavy writers, this implementation caused double write of all data, since the log records were explicitly prepared for SLOG. Since we now have I/O scheduler, I've found it can be much more efficient to reduce priority of heavy logger SLOG writes from ZIO_PRIORITY_SYNC_WRITE to ZIO_PRIORITY_ASYNC_WRITE, while still leave them on SLOG. Existing ZIL implementation had problem with space efficiency when it has to write large chunks of data into log blocks of limited size. In some cases efficiency stopped to almost as low as 50%. In case of ZIL stored on spinning rust, that also reduced log write speed in half, since head had to uselessly fly over allocated but not written areas. This change improves the situation by offloading problematic operations from z*_log_write() to zil_lwb_commit(), which knows real situation of log blocks allocation and can split large requests into pieces much more efficiently. Also as side effect it removes one of two data copy operations done by ZIL code WR_COPIED case. While there, untangle and unify code of z*_log_write() functions. Also zfs_log_write() alike to zvol_log_write() can now handle writes crossing block boundary, that may also improve efficiency if ZPL is made to do that. Reviewed by: Matthew Ahrens <mahrens@delphix.com> Reviewed by: Prakash Surya <prakash.surya@delphix.com> Reviewed by: Andriy Gapon <avg@FreeBSD.org> Reviewed by: Steven Hartland <steven.hartland@multiplay.co.uk> Reviewed by: Brad Lewis <brad.lewis@delphix.com> Reviewed by: Richard Elling <Richard.Elling@RichardElling.com> Approved by: Robert Mustacchi <rm@joyent.com> Author: Alexander Motin <mav@FreeBSD.org> Modified: vendor/illumos/dist/cmd/ztest/ztest.c Changes in other areas also in this revision: Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/sys/zil.h vendor-sys/illumos/dist/uts/common/fs/zfs/sys/zil_impl.h vendor-sys/illumos/dist/uts/common/fs/zfs/sys/zio.h vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_log.c vendor-sys/illumos/dist/uts/common/fs/zfs/zil.c vendor-sys/illumos/dist/uts/common/fs/zfs/zio.c vendor-sys/illumos/dist/uts/common/fs/zfs/zvol.c Modified: vendor/illumos/dist/cmd/ztest/ztest.c ============================================================================== --- vendor/illumos/dist/cmd/ztest/ztest.c Fri May 26 12:13:27 2017 (r318946) +++ vendor/illumos/dist/cmd/ztest/ztest.c Fri May 26 12:13:58 2017 (r318947) @@ -1377,7 +1377,6 @@ ztest_log_write(ztest_ds_t *zd, dmu_tx_t itx->itx_private = zd; itx->itx_wr_state = write_state; itx->itx_sync = (ztest_random(8) == 0); - itx->itx_sod += (write_state == WR_NEED_COPY ? lr->lr_length : 0); bcopy(&lr->lr_common + 1, &itx->itx_lr + 1, sizeof (*lr) - sizeof (lr_t));
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201705261213.v4QCDxT5097349>