mirror_zfs/lib/libspl/include/sys/time.h

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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#ifndef _LIBSPL_SYS_TIME_H
#define _LIBSPL_SYS_TIME_H
#include <time.h>
#include <sys/types.h>
#include_next <sys/time.h>
#ifndef SEC
#define SEC 1
#endif
#ifndef MILLISEC
#define MILLISEC 1000
#endif
#ifndef MICROSEC
#define MICROSEC 1000000
#endif
#ifndef NANOSEC
#define NANOSEC 1000000000
#endif
#ifndef NSEC_PER_USEC
#define NSEC_PER_USEC 1000L
#endif
#ifndef MSEC2NSEC
OpenZFS 8585 - improve batching done in zil_commit() Authored by: Prakash Surya <prakash.surya@delphix.com> Reviewed by: Brad Lewis <brad.lewis@delphix.com> Reviewed by: Matt Ahrens <mahrens@delphix.com> Reviewed by: George Wilson <george.wilson@delphix.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Approved by: Dan McDonald <danmcd@joyent.com> Ported-by: Prakash Surya <prakash.surya@delphix.com> Problem ======= The current implementation of zil_commit() can introduce significant latency, beyond what is inherent due to the latency of the underlying storage. The additional latency comes from two main problems: 1. When there's outstanding ZIL blocks being written (i.e. there's already a "writer thread" in progress), then any new calls to zil_commit() will block waiting for the currently oustanding ZIL blocks to complete. The blocks written for each "writer thread" is coined a "batch", and there can only ever be a single "batch" being written at a time. When a batch is being written, any new ZIL transactions will have to wait for the next batch to be written, which won't occur until the current batch finishes. As a result, the underlying storage may not be used as efficiently as possible. While "new" threads enter zil_commit() and are blocked waiting for the next batch, it's possible that the underlying storage isn't fully utilized by the current batch of ZIL blocks. In that case, it'd be better to allow these new threads to generate (and issue) a new ZIL block, such that it could be serviced by the underlying storage concurrently with the other ZIL blocks that are being serviced. 2. Any call to zil_commit() must wait for all ZIL blocks in its "batch" to complete, prior to zil_commit() returning. The size of any given batch is proportional to the number of ZIL transaction in the queue at the time that the batch starts processing the queue; which doesn't occur until the previous batch completes. Thus, if there's a lot of transactions in the queue, the batch could be composed of many ZIL blocks, and each call to zil_commit() will have to wait for all of these writes to complete (even if the thread calling zil_commit() only cared about one of the transactions in the batch). To further complicate the situation, these two issues result in the following side effect: 3. If a given batch takes longer to complete than normal, this results in larger batch sizes, which then take longer to complete and further drive up the latency of zil_commit(). This can occur for a number of reasons, including (but not limited to): transient changes in the workload, and storage latency irregularites. Solution ======== The solution attempted by this change has the following goals: 1. no on-disk changes; maintain current on-disk format. 2. modify the "batch size" to be equal to the "ZIL block size". 3. allow new batches to be generated and issued to disk, while there's already batches being serviced by the disk. 4. allow zil_commit() to wait for as few ZIL blocks as possible. 5. use as few ZIL blocks as possible, for the same amount of ZIL transactions, without introducing significant latency to any individual ZIL transaction. i.e. use fewer, but larger, ZIL blocks. In theory, with these goals met, the new allgorithm will allow the following improvements: 1. new ZIL blocks can be generated and issued, while there's already oustanding ZIL blocks being serviced by the storage. 2. the latency of zil_commit() should be proportional to the underlying storage latency, rather than the incoming synchronous workload. Porting Notes ============= Due to the changes made in commit 119a394ab0, the lifetime of an itx structure differs than in OpenZFS. Specifically, the itx structure is kept around until the data associated with the itx is considered to be safe on disk; this is so that the itx's callback can be called after the data is committed to stable storage. Since OpenZFS doesn't have this itx callback mechanism, it's able to destroy the itx structure immediately after the itx is committed to an lwb (before the lwb is written to disk). To support this difference, and to ensure the itx's callbacks can still be called after the itx's data is on disk, a few changes had to be made: * A list of itxs was added to the lwb structure. This list contains all of the itxs that have been committed to the lwb, such that the callbacks for these itxs can be called from zil_lwb_flush_vdevs_done(), after the data for the itxs is committed to disk. * A list of itxs was added on the stack of the zil_process_commit_list() function; the "nolwb_itxs" list. In some circumstances, an itx may not be committed to an lwb (e.g. if allocating the "next" ZIL block on disk fails), so this list is used to keep track of which itxs fall into this state, such that their callbacks can be called after the ZIL's writer pipeline is "stalled". * The logic to actually call the itx's callback was moved into the zil_itx_destroy() function. Since all consumers of zil_itx_destroy() were effectively performing the same logic (i.e. if callback is non-null, call the callback), it seemed like useful code cleanup to consolidate this logic into a single function. Additionally, the existing Linux tracepoint infrastructure dealing with the ZIL's probes and structures had to be updated to reflect these code changes. Specifically: * The "zil__cw1" and "zil__cw2" probes were removed, so they had to be removed from "trace_zil.h" as well. * Some of the zilog structure's fields were removed, which affected the tracepoint definitions of the structure. * New tracepoints had to be added for the following 3 new probes: * zil__process__commit__itx * zil__process__normal__itx * zil__commit__io__error OpenZFS-issue: https://www.illumos.org/issues/8585 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/5d95a3a Closes #6566
2017-12-05 20:39:16 +03:00
#define MSEC2NSEC(m) ((hrtime_t)(m) * (NANOSEC / MILLISEC))
#endif
#ifndef NSEC2MSEC
OpenZFS 8585 - improve batching done in zil_commit() Authored by: Prakash Surya <prakash.surya@delphix.com> Reviewed by: Brad Lewis <brad.lewis@delphix.com> Reviewed by: Matt Ahrens <mahrens@delphix.com> Reviewed by: George Wilson <george.wilson@delphix.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Approved by: Dan McDonald <danmcd@joyent.com> Ported-by: Prakash Surya <prakash.surya@delphix.com> Problem ======= The current implementation of zil_commit() can introduce significant latency, beyond what is inherent due to the latency of the underlying storage. The additional latency comes from two main problems: 1. When there's outstanding ZIL blocks being written (i.e. there's already a "writer thread" in progress), then any new calls to zil_commit() will block waiting for the currently oustanding ZIL blocks to complete. The blocks written for each "writer thread" is coined a "batch", and there can only ever be a single "batch" being written at a time. When a batch is being written, any new ZIL transactions will have to wait for the next batch to be written, which won't occur until the current batch finishes. As a result, the underlying storage may not be used as efficiently as possible. While "new" threads enter zil_commit() and are blocked waiting for the next batch, it's possible that the underlying storage isn't fully utilized by the current batch of ZIL blocks. In that case, it'd be better to allow these new threads to generate (and issue) a new ZIL block, such that it could be serviced by the underlying storage concurrently with the other ZIL blocks that are being serviced. 2. Any call to zil_commit() must wait for all ZIL blocks in its "batch" to complete, prior to zil_commit() returning. The size of any given batch is proportional to the number of ZIL transaction in the queue at the time that the batch starts processing the queue; which doesn't occur until the previous batch completes. Thus, if there's a lot of transactions in the queue, the batch could be composed of many ZIL blocks, and each call to zil_commit() will have to wait for all of these writes to complete (even if the thread calling zil_commit() only cared about one of the transactions in the batch). To further complicate the situation, these two issues result in the following side effect: 3. If a given batch takes longer to complete than normal, this results in larger batch sizes, which then take longer to complete and further drive up the latency of zil_commit(). This can occur for a number of reasons, including (but not limited to): transient changes in the workload, and storage latency irregularites. Solution ======== The solution attempted by this change has the following goals: 1. no on-disk changes; maintain current on-disk format. 2. modify the "batch size" to be equal to the "ZIL block size". 3. allow new batches to be generated and issued to disk, while there's already batches being serviced by the disk. 4. allow zil_commit() to wait for as few ZIL blocks as possible. 5. use as few ZIL blocks as possible, for the same amount of ZIL transactions, without introducing significant latency to any individual ZIL transaction. i.e. use fewer, but larger, ZIL blocks. In theory, with these goals met, the new allgorithm will allow the following improvements: 1. new ZIL blocks can be generated and issued, while there's already oustanding ZIL blocks being serviced by the storage. 2. the latency of zil_commit() should be proportional to the underlying storage latency, rather than the incoming synchronous workload. Porting Notes ============= Due to the changes made in commit 119a394ab0, the lifetime of an itx structure differs than in OpenZFS. Specifically, the itx structure is kept around until the data associated with the itx is considered to be safe on disk; this is so that the itx's callback can be called after the data is committed to stable storage. Since OpenZFS doesn't have this itx callback mechanism, it's able to destroy the itx structure immediately after the itx is committed to an lwb (before the lwb is written to disk). To support this difference, and to ensure the itx's callbacks can still be called after the itx's data is on disk, a few changes had to be made: * A list of itxs was added to the lwb structure. This list contains all of the itxs that have been committed to the lwb, such that the callbacks for these itxs can be called from zil_lwb_flush_vdevs_done(), after the data for the itxs is committed to disk. * A list of itxs was added on the stack of the zil_process_commit_list() function; the "nolwb_itxs" list. In some circumstances, an itx may not be committed to an lwb (e.g. if allocating the "next" ZIL block on disk fails), so this list is used to keep track of which itxs fall into this state, such that their callbacks can be called after the ZIL's writer pipeline is "stalled". * The logic to actually call the itx's callback was moved into the zil_itx_destroy() function. Since all consumers of zil_itx_destroy() were effectively performing the same logic (i.e. if callback is non-null, call the callback), it seemed like useful code cleanup to consolidate this logic into a single function. Additionally, the existing Linux tracepoint infrastructure dealing with the ZIL's probes and structures had to be updated to reflect these code changes. Specifically: * The "zil__cw1" and "zil__cw2" probes were removed, so they had to be removed from "trace_zil.h" as well. * Some of the zilog structure's fields were removed, which affected the tracepoint definitions of the structure. * New tracepoints had to be added for the following 3 new probes: * zil__process__commit__itx * zil__process__normal__itx * zil__commit__io__error OpenZFS-issue: https://www.illumos.org/issues/8585 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/5d95a3a Closes #6566
2017-12-05 20:39:16 +03:00
#define NSEC2MSEC(n) ((n) / (NANOSEC / MILLISEC))
#endif
OpenZFS 8585 - improve batching done in zil_commit() Authored by: Prakash Surya <prakash.surya@delphix.com> Reviewed by: Brad Lewis <brad.lewis@delphix.com> Reviewed by: Matt Ahrens <mahrens@delphix.com> Reviewed by: George Wilson <george.wilson@delphix.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Approved by: Dan McDonald <danmcd@joyent.com> Ported-by: Prakash Surya <prakash.surya@delphix.com> Problem ======= The current implementation of zil_commit() can introduce significant latency, beyond what is inherent due to the latency of the underlying storage. The additional latency comes from two main problems: 1. When there's outstanding ZIL blocks being written (i.e. there's already a "writer thread" in progress), then any new calls to zil_commit() will block waiting for the currently oustanding ZIL blocks to complete. The blocks written for each "writer thread" is coined a "batch", and there can only ever be a single "batch" being written at a time. When a batch is being written, any new ZIL transactions will have to wait for the next batch to be written, which won't occur until the current batch finishes. As a result, the underlying storage may not be used as efficiently as possible. While "new" threads enter zil_commit() and are blocked waiting for the next batch, it's possible that the underlying storage isn't fully utilized by the current batch of ZIL blocks. In that case, it'd be better to allow these new threads to generate (and issue) a new ZIL block, such that it could be serviced by the underlying storage concurrently with the other ZIL blocks that are being serviced. 2. Any call to zil_commit() must wait for all ZIL blocks in its "batch" to complete, prior to zil_commit() returning. The size of any given batch is proportional to the number of ZIL transaction in the queue at the time that the batch starts processing the queue; which doesn't occur until the previous batch completes. Thus, if there's a lot of transactions in the queue, the batch could be composed of many ZIL blocks, and each call to zil_commit() will have to wait for all of these writes to complete (even if the thread calling zil_commit() only cared about one of the transactions in the batch). To further complicate the situation, these two issues result in the following side effect: 3. If a given batch takes longer to complete than normal, this results in larger batch sizes, which then take longer to complete and further drive up the latency of zil_commit(). This can occur for a number of reasons, including (but not limited to): transient changes in the workload, and storage latency irregularites. Solution ======== The solution attempted by this change has the following goals: 1. no on-disk changes; maintain current on-disk format. 2. modify the "batch size" to be equal to the "ZIL block size". 3. allow new batches to be generated and issued to disk, while there's already batches being serviced by the disk. 4. allow zil_commit() to wait for as few ZIL blocks as possible. 5. use as few ZIL blocks as possible, for the same amount of ZIL transactions, without introducing significant latency to any individual ZIL transaction. i.e. use fewer, but larger, ZIL blocks. In theory, with these goals met, the new allgorithm will allow the following improvements: 1. new ZIL blocks can be generated and issued, while there's already oustanding ZIL blocks being serviced by the storage. 2. the latency of zil_commit() should be proportional to the underlying storage latency, rather than the incoming synchronous workload. Porting Notes ============= Due to the changes made in commit 119a394ab0, the lifetime of an itx structure differs than in OpenZFS. Specifically, the itx structure is kept around until the data associated with the itx is considered to be safe on disk; this is so that the itx's callback can be called after the data is committed to stable storage. Since OpenZFS doesn't have this itx callback mechanism, it's able to destroy the itx structure immediately after the itx is committed to an lwb (before the lwb is written to disk). To support this difference, and to ensure the itx's callbacks can still be called after the itx's data is on disk, a few changes had to be made: * A list of itxs was added to the lwb structure. This list contains all of the itxs that have been committed to the lwb, such that the callbacks for these itxs can be called from zil_lwb_flush_vdevs_done(), after the data for the itxs is committed to disk. * A list of itxs was added on the stack of the zil_process_commit_list() function; the "nolwb_itxs" list. In some circumstances, an itx may not be committed to an lwb (e.g. if allocating the "next" ZIL block on disk fails), so this list is used to keep track of which itxs fall into this state, such that their callbacks can be called after the ZIL's writer pipeline is "stalled". * The logic to actually call the itx's callback was moved into the zil_itx_destroy() function. Since all consumers of zil_itx_destroy() were effectively performing the same logic (i.e. if callback is non-null, call the callback), it seemed like useful code cleanup to consolidate this logic into a single function. Additionally, the existing Linux tracepoint infrastructure dealing with the ZIL's probes and structures had to be updated to reflect these code changes. Specifically: * The "zil__cw1" and "zil__cw2" probes were removed, so they had to be removed from "trace_zil.h" as well. * Some of the zilog structure's fields were removed, which affected the tracepoint definitions of the structure. * New tracepoints had to be added for the following 3 new probes: * zil__process__commit__itx * zil__process__normal__itx * zil__commit__io__error OpenZFS-issue: https://www.illumos.org/issues/8585 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/5d95a3a Closes #6566
2017-12-05 20:39:16 +03:00
#ifndef USEC2NSEC
#define USEC2NSEC(m) ((hrtime_t)(m) * (NANOSEC / MICROSEC))
#endif
#ifndef NSEC2USEC
#define NSEC2USEC(n) ((n) / (NANOSEC / MICROSEC))
#endif
#ifndef NSEC2SEC
#define NSEC2SEC(n) ((n) / (NANOSEC / SEC))
#endif
#ifndef SEC2NSEC
#define SEC2NSEC(m) ((hrtime_t)(m) * (NANOSEC / SEC))
#endif
typedef long long hrtime_t;
typedef struct timespec timespec_t;
typedef struct timespec inode_timespec_t;
static inline void
gethrestime(inode_timespec_t *ts)
{
struct timeval tv;
(void) gettimeofday(&tv, NULL);
ts->tv_sec = tv.tv_sec;
ts->tv_nsec = tv.tv_usec * NSEC_PER_USEC;
}
static inline time_t
gethrestime_sec(void)
{
struct timeval tv;
(void) gettimeofday(&tv, NULL);
return (tv.tv_sec);
}
static inline hrtime_t
gethrtime(void)
{
struct timespec ts;
(void) clock_gettime(CLOCK_MONOTONIC, &ts);
return ((((u_int64_t)ts.tv_sec) * NANOSEC) + ts.tv_nsec);
}
#endif /* _LIBSPL_SYS_TIME_H */