On Tue, Jun 04, 2019 at 02:50:20PM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > > Create a parallel iwalk implementation and switch quotacheck to use it. > > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > --- Interesting.. is there any commonality here with the ktask mechanism that's been in progress? I've not followed the details, but I thought it was a similar idea. The last post I see for that is here: https://marc.info/?l=linux-mm&m=154143701122927&w=2 That aside, this all looks mostly fine to me. A few random thoughts.. > fs/xfs/Makefile | 1 > fs/xfs/xfs_globals.c | 3 + > fs/xfs/xfs_iwalk.c | 76 ++++++++++++++++++++++++++++++- > fs/xfs/xfs_iwalk.h | 2 + > fs/xfs/xfs_pwork.c | 122 ++++++++++++++++++++++++++++++++++++++++++++++++++ > fs/xfs/xfs_pwork.h | 50 ++++++++++++++++++++ > fs/xfs/xfs_qm.c | 2 - > fs/xfs/xfs_sysctl.h | 6 ++ > fs/xfs/xfs_sysfs.c | 40 ++++++++++++++++ > fs/xfs/xfs_trace.h | 18 +++++++ > 10 files changed, 317 insertions(+), 3 deletions(-) > create mode 100644 fs/xfs/xfs_pwork.c > create mode 100644 fs/xfs/xfs_pwork.h > > > diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile > index 74d30ef0dbce..48940a27d4aa 100644 > --- a/fs/xfs/Makefile > +++ b/fs/xfs/Makefile > @@ -84,6 +84,7 @@ xfs-y += xfs_aops.o \ > xfs_message.o \ > xfs_mount.o \ > xfs_mru_cache.o \ > + xfs_pwork.o \ > xfs_reflink.o \ > xfs_stats.o \ > xfs_super.o \ > diff --git a/fs/xfs/xfs_globals.c b/fs/xfs/xfs_globals.c > index d0d377384120..4f93f2c4dc38 100644 > --- a/fs/xfs/xfs_globals.c > +++ b/fs/xfs/xfs_globals.c > @@ -31,6 +31,9 @@ xfs_param_t xfs_params = { > .fstrm_timer = { 1, 30*100, 3600*100}, > .eofb_timer = { 1, 300, 3600*24}, > .cowb_timer = { 1, 1800, 3600*24}, > +#ifdef DEBUG > + .pwork_threads = { 0, 0, NR_CPUS }, > +#endif > }; > > struct xfs_globals xfs_globals = { > diff --git a/fs/xfs/xfs_iwalk.c b/fs/xfs/xfs_iwalk.c > index 8595258b5001..71ee1628aa70 100644 > --- a/fs/xfs/xfs_iwalk.c > +++ b/fs/xfs/xfs_iwalk.c > @@ -21,6 +21,7 @@ > #include "xfs_health.h" > #include "xfs_trans.h" > #include "xfs_iwalk.h" > +#include "xfs_pwork.h" > > /* > * Walking Inodes in the Filesystem > @@ -46,6 +47,9 @@ > */ > > struct xfs_iwalk_ag { > + /* parallel work control data; will be null if single threaded */ > + struct xfs_pwork pwork; > + > struct xfs_mount *mp; > struct xfs_trans *tp; > > @@ -200,6 +204,9 @@ xfs_iwalk_ag_recs( > trace_xfs_iwalk_ag_rec(mp, agno, irec); > > for (j = 0; j < XFS_INODES_PER_CHUNK; j++) { > + if (xfs_pwork_want_abort(&iwag->pwork)) > + return 0; > + > /* Skip if this inode is free */ > if (XFS_INOBT_MASK(j) & irec->ir_free) > continue; > @@ -360,7 +367,7 @@ xfs_iwalk_ag( > agino = XFS_INO_TO_AGINO(mp, iwag->startino); > error = xfs_iwalk_ag_start(iwag, agno, agino, &cur, &agi_bp, &has_more); > > - while (!error && has_more) { > + while (!error && has_more && !xfs_pwork_want_abort(&iwag->pwork)) { > struct xfs_inobt_rec_incore *irec; > > cond_resched(); > @@ -409,7 +416,7 @@ xfs_iwalk_ag( > xfs_iwalk_del_inobt(tp, &cur, &agi_bp, error); > > /* Walk any records left behind in the cache. */ > - if (iwag->nr_recs == 0 || error) > + if (iwag->nr_recs == 0 || error || xfs_pwork_want_abort(&iwag->pwork)) > return error; > > return xfs_iwalk_ag_recs(iwag); > @@ -465,6 +472,7 @@ xfs_iwalk( > .iwalk_fn = iwalk_fn, > .data = data, > .startino = startino, > + .pwork = XFS_PWORK_SINGLE_THREADED, > }; > xfs_agnumber_t agno = XFS_INO_TO_AGNO(mp, startino); > int error; > @@ -486,3 +494,67 @@ xfs_iwalk( > xfs_iwalk_free(&iwag); > return error; > } > + > +/* Run per-thread iwalk work. */ > +static int > +xfs_iwalk_ag_work( > + struct xfs_mount *mp, > + struct xfs_pwork *pwork) > +{ > + struct xfs_iwalk_ag *iwag; > + int error; > + > + iwag = container_of(pwork, struct xfs_iwalk_ag, pwork); > + error = xfs_iwalk_alloc(iwag); > + if (error) > + goto out; In most cases this will never fail, but the error path if it does looks slightly painful. I was thinking if we could move this up into xfs_iwalk_threaded() so we wouldn't continue to queue work jobs when failure is imminent... > + > + error = xfs_iwalk_ag(iwag); > + xfs_iwalk_free(iwag); > +out: > + kmem_free(iwag); > + return error; > +} > + > +/* > + * Walk all the inodes in the filesystem using multiple threads to process each > + * AG. > + */ > +int > +xfs_iwalk_threaded( > + struct xfs_mount *mp, > + xfs_ino_t startino, > + xfs_iwalk_fn iwalk_fn, > + unsigned int max_prefetch, > + void *data) > +{ > + struct xfs_pwork_ctl pctl; > + xfs_agnumber_t agno = XFS_INO_TO_AGNO(mp, startino); > + unsigned int nr_threads; > + int error; > + > + ASSERT(agno < mp->m_sb.sb_agcount); > + > + nr_threads = xfs_pwork_guess_datadev_parallelism(mp); > + error = xfs_pwork_init(mp, &pctl, xfs_iwalk_ag_work, "xfs_iwalk", > + nr_threads); > + if (error) > + return error; > + > + for (; agno < mp->m_sb.sb_agcount; agno++) { > + struct xfs_iwalk_ag *iwag; > + > + iwag = kmem_alloc(sizeof(struct xfs_iwalk_ag), KM_SLEEP); > + iwag->mp = mp; > + iwag->tp = NULL; > + iwag->iwalk_fn = iwalk_fn; > + iwag->data = data; > + iwag->startino = startino; > + iwag->recs = NULL; > + xfs_iwalk_set_prefetch(iwag, max_prefetch); > + xfs_pwork_queue(&pctl, &iwag->pwork); > + startino = XFS_AGINO_TO_INO(mp, agno + 1, 0); > + } ... but this is only bound by the number of AGs and so could result in a large number of allocations. FWIW, I wouldn't expect that to be a problem in the common case. I'm more thinking about the case of a specially crafted filesystem designed to cause problems on mount. > + > + return xfs_pwork_destroy(&pctl); > +} > diff --git a/fs/xfs/xfs_iwalk.h b/fs/xfs/xfs_iwalk.h > index 45b1baabcd2d..40233a05a766 100644 > --- a/fs/xfs/xfs_iwalk.h > +++ b/fs/xfs/xfs_iwalk.h > @@ -14,5 +14,7 @@ typedef int (*xfs_iwalk_fn)(struct xfs_mount *mp, struct xfs_trans *tp, > > int xfs_iwalk(struct xfs_mount *mp, struct xfs_trans *tp, xfs_ino_t startino, > xfs_iwalk_fn iwalk_fn, unsigned int max_prefetch, void *data); > +int xfs_iwalk_threaded(struct xfs_mount *mp, xfs_ino_t startino, > + xfs_iwalk_fn iwalk_fn, unsigned int max_prefetch, void *data); > > #endif /* __XFS_IWALK_H__ */ > diff --git a/fs/xfs/xfs_pwork.c b/fs/xfs/xfs_pwork.c > new file mode 100644 > index 000000000000..19605a3a2482 > --- /dev/null > +++ b/fs/xfs/xfs_pwork.c > @@ -0,0 +1,122 @@ > +// SPDX-License-Identifier: GPL-2.0+ > +/* > + * Copyright (C) 2019 Oracle. All Rights Reserved. > + * Author: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > + */ > +#include "xfs.h" > +#include "xfs_fs.h" > +#include "xfs_shared.h" > +#include "xfs_format.h" > +#include "xfs_log_format.h" > +#include "xfs_trans_resv.h" > +#include "xfs_mount.h" > +#include "xfs_trace.h" > +#include "xfs_sysctl.h" > +#include "xfs_pwork.h" > + > +/* > + * Parallel Work Queue > + * =================== > + * > + * Abstract away the details of running a large and "obviously" parallelizable > + * task across multiple CPUs. Callers initialize the pwork control object with > + * a desired level of parallelization and a work function. Next, they embed > + * struct xfs_pwork in whatever structure they use to pass work context to a > + * worker thread and queue that pwork. The work function will be passed the > + * pwork item when it is run (from process context) and any returned error will > + * cause all threads to abort. > + * FYI minor whitespace damage (trailing space) on the line above. > + * This is the rough equivalent of the xfsprogs workqueue code, though we can't > + * reuse that name here. > + */ > + > +/* Invoke our caller's function. */ > +static void > +xfs_pwork_work( > + struct work_struct *work) > +{ > + struct xfs_pwork *pwork; > + struct xfs_pwork_ctl *pctl; > + int error; > + > + pwork = container_of(work, struct xfs_pwork, work); > + pctl = pwork->pctl; > + error = pctl->work_fn(pctl->mp, pwork); > + if (error && !pctl->error) > + pctl->error = error; > +} > + > +/* > + * Set up control data for parallel work. @work_fn is the function that will > + * be called. @tag will be written into the kernel threads. @nr_threads is > + * the level of parallelism desired, or 0 for no limit. > + */ > +int > +xfs_pwork_init( > + struct xfs_mount *mp, > + struct xfs_pwork_ctl *pctl, > + xfs_pwork_work_fn work_fn, > + const char *tag, > + unsigned int nr_threads) > +{ > +#ifdef DEBUG > + if (xfs_globals.pwork_threads > 0) > + nr_threads = xfs_globals.pwork_threads; > +#endif Hmm, it might be useful to have the ability to force the no limit case from the debug knob. Can we use -1 or something here for "disabled?" > + trace_xfs_pwork_init(mp, nr_threads, current->pid); > + > + pctl->wq = alloc_workqueue("%s-%d", WQ_FREEZABLE, nr_threads, tag, > + current->pid); > + if (!pctl->wq) > + return -ENOMEM; > + pctl->work_fn = work_fn; > + pctl->error = 0; > + pctl->mp = mp; > + > + return 0; > +} > + > +/* Queue some parallel work. */ > +void > +xfs_pwork_queue( > + struct xfs_pwork_ctl *pctl, > + struct xfs_pwork *pwork) > +{ > + INIT_WORK(&pwork->work, xfs_pwork_work); > + pwork->pctl = pctl; > + queue_work(pctl->wq, &pwork->work); > +} > + > +/* Wait for the work to finish and tear down the control structure. */ > +int > +xfs_pwork_destroy( > + struct xfs_pwork_ctl *pctl) > +{ > + destroy_workqueue(pctl->wq); > + pctl->wq = NULL; > + return pctl->error; > +} > + > +/* > + * Return the amount of parallelism that the data device can handle, or 0 for > + * no limit. > + */ > +unsigned int > +xfs_pwork_guess_datadev_parallelism( > + struct xfs_mount *mp) > +{ > + struct xfs_buftarg *btp = mp->m_ddev_targp; > + int iomin; > + int ioopt; > + > + if (blk_queue_nonrot(btp->bt_bdev->bd_queue)) > + return num_online_cpus(); > + if (mp->m_sb.sb_width && mp->m_sb.sb_unit) > + return mp->m_sb.sb_width / mp->m_sb.sb_unit; > + iomin = bdev_io_min(btp->bt_bdev); > + ioopt = bdev_io_opt(btp->bt_bdev); > + if (iomin && ioopt) > + return ioopt / iomin; > + > + return 1; Have you collected any performance data related to these heuristics? I assume the feature is generally a win, but this also seems like we have a large window of variance here. E.g., an SSD on a server with hundreds of CPUs will enable as many threads as CPUs, but a single xTB spindle on the same box may run single threaded (a quick check of a few local devices all return an optimal I/O size of 0). Is there really no benefit parallelizing some of that work in the spinning rust case? What about in the other direction where we might have a ton of threads for inodes across AGs that all happen to be in the same project quota, for example? Brian > +} > diff --git a/fs/xfs/xfs_pwork.h b/fs/xfs/xfs_pwork.h > new file mode 100644 > index 000000000000..e0c1354a2d8c > --- /dev/null > +++ b/fs/xfs/xfs_pwork.h > @@ -0,0 +1,50 @@ > +// SPDX-License-Identifier: GPL-2.0+ > +/* > + * Copyright (C) 2019 Oracle. All Rights Reserved. > + * Author: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > + */ > +#ifndef __XFS_PWORK_H__ > +#define __XFS_PWORK_H__ > + > +struct xfs_pwork; > +struct xfs_mount; > + > +typedef int (*xfs_pwork_work_fn)(struct xfs_mount *mp, struct xfs_pwork *pwork); > + > +/* > + * Parallel work coordination structure. > + */ > +struct xfs_pwork_ctl { > + struct workqueue_struct *wq; > + struct xfs_mount *mp; > + xfs_pwork_work_fn work_fn; > + int error; > +}; > + > +/* > + * Embed this parallel work control item inside your own work structure, > + * then queue work with it. > + */ > +struct xfs_pwork { > + struct work_struct work; > + struct xfs_pwork_ctl *pctl; > +}; > + > +#define XFS_PWORK_SINGLE_THREADED { .pctl = NULL } > + > +/* Have we been told to abort? */ > +static inline bool > +xfs_pwork_want_abort( > + struct xfs_pwork *pwork) > +{ > + return pwork->pctl && pwork->pctl->error; > +} > + > +int xfs_pwork_init(struct xfs_mount *mp, struct xfs_pwork_ctl *pctl, > + xfs_pwork_work_fn work_fn, const char *tag, > + unsigned int nr_threads); > +void xfs_pwork_queue(struct xfs_pwork_ctl *pctl, struct xfs_pwork *pwork); > +int xfs_pwork_destroy(struct xfs_pwork_ctl *pctl); > +unsigned int xfs_pwork_guess_datadev_parallelism(struct xfs_mount *mp); > + > +#endif /* __XFS_PWORK_H__ */ > diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c > index a5b2260406a8..e4f3785f7a64 100644 > --- a/fs/xfs/xfs_qm.c > +++ b/fs/xfs/xfs_qm.c > @@ -1305,7 +1305,7 @@ xfs_qm_quotacheck( > flags |= XFS_PQUOTA_CHKD; > } > > - error = xfs_iwalk(mp, NULL, 0, xfs_qm_dqusage_adjust, 0, NULL); > + error = xfs_iwalk_threaded(mp, 0, xfs_qm_dqusage_adjust, 0, NULL); > if (error) > goto error_return; > > diff --git a/fs/xfs/xfs_sysctl.h b/fs/xfs/xfs_sysctl.h > index ad7f9be13087..b555e045e2f4 100644 > --- a/fs/xfs/xfs_sysctl.h > +++ b/fs/xfs/xfs_sysctl.h > @@ -37,6 +37,9 @@ typedef struct xfs_param { > xfs_sysctl_val_t fstrm_timer; /* Filestream dir-AG assoc'n timeout. */ > xfs_sysctl_val_t eofb_timer; /* Interval between eofb scan wakeups */ > xfs_sysctl_val_t cowb_timer; /* Interval between cowb scan wakeups */ > +#ifdef DEBUG > + xfs_sysctl_val_t pwork_threads; /* Parallel workqueue thread count */ > +#endif > } xfs_param_t; > > /* > @@ -82,6 +85,9 @@ enum { > extern xfs_param_t xfs_params; > > struct xfs_globals { > +#ifdef DEBUG > + int pwork_threads; /* parallel workqueue threads */ > +#endif > int log_recovery_delay; /* log recovery delay (secs) */ > int mount_delay; /* mount setup delay (secs) */ > bool bug_on_assert; /* BUG() the kernel on assert failure */ > diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c > index cabda13f3c64..910e6b9cb1a7 100644 > --- a/fs/xfs/xfs_sysfs.c > +++ b/fs/xfs/xfs_sysfs.c > @@ -206,11 +206,51 @@ always_cow_show( > } > XFS_SYSFS_ATTR_RW(always_cow); > > +#ifdef DEBUG > +/* > + * Override how many threads the parallel work queue is allowed to create. > + * This has to be a debug-only global (instead of an errortag) because one of > + * the main users of parallel workqueues is mount time quotacheck. > + */ > +STATIC ssize_t > +pwork_threads_store( > + struct kobject *kobject, > + const char *buf, > + size_t count) > +{ > + int ret; > + int val; > + > + ret = kstrtoint(buf, 0, &val); > + if (ret) > + return ret; > + > + if (val < 0 || val > NR_CPUS) > + return -EINVAL; > + > + xfs_globals.pwork_threads = val; > + > + return count; > +} > + > +STATIC ssize_t > +pwork_threads_show( > + struct kobject *kobject, > + char *buf) > +{ > + return snprintf(buf, PAGE_SIZE, "%d\n", xfs_globals.pwork_threads); > +} > +XFS_SYSFS_ATTR_RW(pwork_threads); > +#endif /* DEBUG */ > + > static struct attribute *xfs_dbg_attrs[] = { > ATTR_LIST(bug_on_assert), > ATTR_LIST(log_recovery_delay), > ATTR_LIST(mount_delay), > ATTR_LIST(always_cow), > +#ifdef DEBUG > + ATTR_LIST(pwork_threads), > +#endif > NULL, > }; > > diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h > index f9bb1d50bc0e..658cbade1998 100644 > --- a/fs/xfs/xfs_trace.h > +++ b/fs/xfs/xfs_trace.h > @@ -3556,6 +3556,24 @@ TRACE_EVENT(xfs_iwalk_ag_rec, > __entry->startino, __entry->freemask) > ) > > +TRACE_EVENT(xfs_pwork_init, > + TP_PROTO(struct xfs_mount *mp, unsigned int nr_threads, pid_t pid), > + TP_ARGS(mp, nr_threads, pid), > + TP_STRUCT__entry( > + __field(dev_t, dev) > + __field(unsigned int, nr_threads) > + __field(pid_t, pid) > + ), > + TP_fast_assign( > + __entry->dev = mp->m_super->s_dev; > + __entry->nr_threads = nr_threads; > + __entry->pid = pid; > + ), > + TP_printk("dev %d:%d nr_threads %u pid %u", > + MAJOR(__entry->dev), MINOR(__entry->dev), > + __entry->nr_threads, __entry->pid) > +) > + > #endif /* _TRACE_XFS_H */ > > #undef TRACE_INCLUDE_PATH >
