* [PATCH] Documentation: RCU: arrayRCU: Converted arrayRCU.txt to arrayRCU.rst @ 2019-10-28 20:24 madhuparnabhowmik04 2019-10-28 21:00 ` Paul E. McKenney 2019-11-05 13:49 ` [Linux-kernel-mentees] " Phong Tran 0 siblings, 2 replies; 6+ messages in thread From: madhuparnabhowmik04 @ 2019-10-28 20:24 UTC (permalink / raw) To: paulmck, joel, corbet Cc: linux-doc, rcu, linux-kernel, linux-kernel-mentees, Madhuparna Bhowmik From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> This patch converts arrayRCU from txt to rst format. arrayRCU.rst is also added in the index.rst file. Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> --- .../RCU/{arrayRCU.txt => arrayRCU.rst} | 18 +++++++++++++----- Documentation/RCU/index.rst | 1 + 2 files changed, 14 insertions(+), 5 deletions(-) rename Documentation/RCU/{arrayRCU.txt => arrayRCU.rst} (91%) diff --git a/Documentation/RCU/arrayRCU.txt b/Documentation/RCU/arrayRCU.rst similarity index 91% rename from Documentation/RCU/arrayRCU.txt rename to Documentation/RCU/arrayRCU.rst index f05a9afb2c39..ed5ae24b196e 100644 --- a/Documentation/RCU/arrayRCU.txt +++ b/Documentation/RCU/arrayRCU.rst @@ -1,5 +1,7 @@ -Using RCU to Protect Read-Mostly Arrays +.. _array_rcu_doc: +Using RCU to Protect Read-Mostly Arrays +======================================= Although RCU is more commonly used to protect linked lists, it can also be used to protect arrays. Three situations are as follows: @@ -26,6 +28,7 @@ described in the following sections. Situation 1: Hash Tables +------------------------ Hash tables are often implemented as an array, where each array entry has a linked-list hash chain. Each hash chain can be protected by RCU @@ -34,6 +37,7 @@ to other array-of-list situations, such as radix trees. Situation 2: Static Arrays +-------------------------- Static arrays, where the data (rather than a pointer to the data) is located in each array element, and where the array is never resized, @@ -41,11 +45,13 @@ have not been used with RCU. Rik van Riel recommends using seqlock in this situation, which would also have minimal read-side overhead as long as updates are rare. -Quick Quiz: Why is it so important that updates be rare when - using seqlock? +Quick Quiz: + Why is it so important that updates be rare when using seqlock? +:ref:`Answer to Quick Quiz <answer_quick_quiz_seqlock>` Situation 3: Resizeable Arrays +------------------------------ Use of RCU for resizeable arrays is demonstrated by the grow_ary() function formerly used by the System V IPC code. The array is used @@ -60,7 +66,7 @@ the remainder of the new, updates the ids->entries pointer to point to the new array, and invokes ipc_rcu_putref() to free up the old array. Note that rcu_assign_pointer() is used to update the ids->entries pointer, which includes any memory barriers required on whatever architecture -you are running on. +you are running on.:: static int grow_ary(struct ipc_ids* ids, int newsize) { @@ -112,7 +118,7 @@ a simple check suffices. The pointer to the structure corresponding to the desired IPC object is placed in "out", with NULL indicating a non-existent entry. After acquiring "out->lock", the "out->deleted" flag indicates whether the IPC object is in the process of being -deleted, and, if not, the pointer is returned. +deleted, and, if not, the pointer is returned.:: struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id) { @@ -144,8 +150,10 @@ deleted, and, if not, the pointer is returned. return out; } +.. _answer_quick_quiz_seqlock: Answer to Quick Quiz: + Why is it so important that updates be rare when using seqlock? The reason that it is important that updates be rare when using seqlock is that frequent updates can livelock readers. diff --git a/Documentation/RCU/index.rst b/Documentation/RCU/index.rst index 5c99185710fa..8d20d44f8fd4 100644 --- a/Documentation/RCU/index.rst +++ b/Documentation/RCU/index.rst @@ -7,6 +7,7 @@ RCU concepts .. toctree:: :maxdepth: 3 + arrayRCU rcu listRCU UP -- 2.17.1 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] Documentation: RCU: arrayRCU: Converted arrayRCU.txt to arrayRCU.rst 2019-10-28 20:24 [PATCH] Documentation: RCU: arrayRCU: Converted arrayRCU.txt to arrayRCU.rst madhuparnabhowmik04 @ 2019-10-28 21:00 ` Paul E. McKenney 2019-11-05 13:49 ` [Linux-kernel-mentees] " Phong Tran 1 sibling, 0 replies; 6+ messages in thread From: Paul E. McKenney @ 2019-10-28 21:00 UTC (permalink / raw) To: madhuparnabhowmik04 Cc: paulmck, joel, corbet, linux-doc, rcu, linux-kernel, linux-kernel-mentees On Tue, Oct 29, 2019 at 01:54:17AM +0530, madhuparnabhowmik04@gmail.com wrote: > From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> > > This patch converts arrayRCU from txt to rst format. > arrayRCU.rst is also added in the index.rst file. > > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> Much better, thank you! I queued this with a small but important change called out below. > --- > .../RCU/{arrayRCU.txt => arrayRCU.rst} | 18 +++++++++++++----- > Documentation/RCU/index.rst | 1 + > 2 files changed, 14 insertions(+), 5 deletions(-) > rename Documentation/RCU/{arrayRCU.txt => arrayRCU.rst} (91%) > > diff --git a/Documentation/RCU/arrayRCU.txt b/Documentation/RCU/arrayRCU.rst > similarity index 91% > rename from Documentation/RCU/arrayRCU.txt > rename to Documentation/RCU/arrayRCU.rst > index f05a9afb2c39..ed5ae24b196e 100644 > --- a/Documentation/RCU/arrayRCU.txt > +++ b/Documentation/RCU/arrayRCU.rst > @@ -1,5 +1,7 @@ > -Using RCU to Protect Read-Mostly Arrays > +.. _array_rcu_doc: > > +Using RCU to Protect Read-Mostly Arrays > +======================================= > > Although RCU is more commonly used to protect linked lists, it can > also be used to protect arrays. Three situations are as follows: > @@ -26,6 +28,7 @@ described in the following sections. > > > Situation 1: Hash Tables > +------------------------ > > Hash tables are often implemented as an array, where each array entry > has a linked-list hash chain. Each hash chain can be protected by RCU > @@ -34,6 +37,7 @@ to other array-of-list situations, such as radix trees. > > > Situation 2: Static Arrays > +-------------------------- > > Static arrays, where the data (rather than a pointer to the data) is > located in each array element, and where the array is never resized, > @@ -41,11 +45,13 @@ have not been used with RCU. Rik van Riel recommends using seqlock in > this situation, which would also have minimal read-side overhead as long > as updates are rare. > > -Quick Quiz: Why is it so important that updates be rare when > - using seqlock? > +Quick Quiz: The above line added trailing whitespace. I removed it for you, but please check for this on future submissions. ;-) Thanx, Paul > + Why is it so important that updates be rare when using seqlock? > > +:ref:`Answer to Quick Quiz <answer_quick_quiz_seqlock>` > > Situation 3: Resizeable Arrays > +------------------------------ > > Use of RCU for resizeable arrays is demonstrated by the grow_ary() > function formerly used by the System V IPC code. The array is used > @@ -60,7 +66,7 @@ the remainder of the new, updates the ids->entries pointer to point to > the new array, and invokes ipc_rcu_putref() to free up the old array. > Note that rcu_assign_pointer() is used to update the ids->entries pointer, > which includes any memory barriers required on whatever architecture > -you are running on. > +you are running on.:: > > static int grow_ary(struct ipc_ids* ids, int newsize) > { > @@ -112,7 +118,7 @@ a simple check suffices. The pointer to the structure corresponding > to the desired IPC object is placed in "out", with NULL indicating > a non-existent entry. After acquiring "out->lock", the "out->deleted" > flag indicates whether the IPC object is in the process of being > -deleted, and, if not, the pointer is returned. > +deleted, and, if not, the pointer is returned.:: > > struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id) > { > @@ -144,8 +150,10 @@ deleted, and, if not, the pointer is returned. > return out; > } > > +.. _answer_quick_quiz_seqlock: > > Answer to Quick Quiz: > + Why is it so important that updates be rare when using seqlock? > > The reason that it is important that updates be rare when > using seqlock is that frequent updates can livelock readers. > diff --git a/Documentation/RCU/index.rst b/Documentation/RCU/index.rst > index 5c99185710fa..8d20d44f8fd4 100644 > --- a/Documentation/RCU/index.rst > +++ b/Documentation/RCU/index.rst > @@ -7,6 +7,7 @@ RCU concepts > .. toctree:: > :maxdepth: 3 > > + arrayRCU > rcu > listRCU > UP > -- > 2.17.1 > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH] Documentation: RCU: arrayRCU: Converted arrayRCU.txt to arrayRCU.rst 2019-10-28 20:24 [PATCH] Documentation: RCU: arrayRCU: Converted arrayRCU.txt to arrayRCU.rst madhuparnabhowmik04 2019-10-28 21:00 ` Paul E. McKenney @ 2019-11-05 13:49 ` Phong Tran 2019-11-05 14:04 ` Paul E. McKenney 1 sibling, 1 reply; 6+ messages in thread From: Phong Tran @ 2019-11-05 13:49 UTC (permalink / raw) To: madhuparnabhowmik04 Cc: paulmck, joel, corbet, tranmanphong, rcu, linux-kernel-mentees, linux-kernel, linux-doc On 10/29/19 3:24 AM, madhuparnabhowmik04@gmail.com wrote: > From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> > > This patch converts arrayRCU from txt to rst format. > arrayRCU.rst is also added in the index.rst file. > > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> > --- > .../RCU/{arrayRCU.txt => arrayRCU.rst} | 18 +++++++++++++----- > Documentation/RCU/index.rst | 1 + > 2 files changed, 14 insertions(+), 5 deletions(-) > rename Documentation/RCU/{arrayRCU.txt => arrayRCU.rst} (91%) > > diff --git a/Documentation/RCU/arrayRCU.txt b/Documentation/RCU/arrayRCU.rst > similarity index 91% > rename from Documentation/RCU/arrayRCU.txt > rename to Documentation/RCU/arrayRCU.rst > index f05a9afb2c39..ed5ae24b196e 100644 > --- a/Documentation/RCU/arrayRCU.txt > +++ b/Documentation/RCU/arrayRCU.rst > @@ -1,5 +1,7 @@ > -Using RCU to Protect Read-Mostly Arrays > +.. _array_rcu_doc: > > +Using RCU to Protect Read-Mostly Arrays > +======================================= > > Although RCU is more commonly used to protect linked lists, it can > also be used to protect arrays. Three situations are as follows: > @@ -26,6 +28,7 @@ described in the following sections. > > It will be better to have the cross reference for each situation. Hash Tables Static Arrays Resizeable Arrays > Situation 1: Hash Tables > +------------------------ > > Hash tables are often implemented as an array, where each array entry > has a linked-list hash chain. Each hash chain can be protected by RCU > @@ -34,6 +37,7 @@ to other array-of-list situations, such as radix trees. > > > Situation 2: Static Arrays > +-------------------------- > > Static arrays, where the data (rather than a pointer to the data) is > located in each array element, and where the array is never resized, > @@ -41,11 +45,13 @@ have not been used with RCU. Rik van Riel recommends using seqlock in > this situation, which would also have minimal read-side overhead as long > as updates are rare. > > -Quick Quiz: Why is it so important that updates be rare when > - using seqlock? > +Quick Quiz: > + Why is it so important that updates be rare when using seqlock? > > +:ref:`Answer to Quick Quiz <answer_quick_quiz_seqlock>` > > Situation 3: Resizeable Arrays > +------------------------------ > > Use of RCU for resizeable arrays is demonstrated by the grow_ary() > function formerly used by the System V IPC code. The array is used > @@ -60,7 +66,7 @@ the remainder of the new, updates the ids->entries pointer to point to > the new array, and invokes ipc_rcu_putref() to free up the old array. > Note that rcu_assign_pointer() is used to update the ids->entries pointer, > which includes any memory barriers required on whatever architecture > -you are running on. > +you are running on.:: > a redundant ":" in here with html page. > static int grow_ary(struct ipc_ids* ids, int newsize) > { > @@ -112,7 +118,7 @@ a simple check suffices. The pointer to the structure corresponding > to the desired IPC object is placed in "out", with NULL indicating > a non-existent entry. After acquiring "out->lock", the "out->deleted" > flag indicates whether the IPC object is in the process of being > -deleted, and, if not, the pointer is returned. > +deleted, and, if not, the pointer is returned.:: > same as above Tested-by: Phong Tran <tranmanphong@gmail.com> Regards, Phong. > struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id) > { > @@ -144,8 +150,10 @@ deleted, and, if not, the pointer is returned. > return out; > } > > +.. _answer_quick_quiz_seqlock: > > Answer to Quick Quiz: > + Why is it so important that updates be rare when using seqlock? > > The reason that it is important that updates be rare when > using seqlock is that frequent updates can livelock readers. > diff --git a/Documentation/RCU/index.rst b/Documentation/RCU/index.rst > index 5c99185710fa..8d20d44f8fd4 100644 > --- a/Documentation/RCU/index.rst > +++ b/Documentation/RCU/index.rst > @@ -7,6 +7,7 @@ RCU concepts > .. toctree:: > :maxdepth: 3 > > + arrayRCU > rcu > listRCU > UP > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH] Documentation: RCU: arrayRCU: Converted arrayRCU.txt to arrayRCU.rst 2019-11-05 13:49 ` [Linux-kernel-mentees] " Phong Tran @ 2019-11-05 14:04 ` Paul E. McKenney 2019-11-05 14:33 ` Amol Grover 0 siblings, 1 reply; 6+ messages in thread From: Paul E. McKenney @ 2019-11-05 14:04 UTC (permalink / raw) To: Phong Tran Cc: madhuparnabhowmik04, joel, corbet, rcu, linux-kernel-mentees, linux-kernel, linux-doc On Tue, Nov 05, 2019 at 08:49:47PM +0700, Phong Tran wrote: > On 10/29/19 3:24 AM, madhuparnabhowmik04@gmail.com wrote: > > From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> > > > > This patch converts arrayRCU from txt to rst format. > > arrayRCU.rst is also added in the index.rst file. > > > > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> > > --- > > .../RCU/{arrayRCU.txt => arrayRCU.rst} | 18 +++++++++++++----- > > Documentation/RCU/index.rst | 1 + > > 2 files changed, 14 insertions(+), 5 deletions(-) > > rename Documentation/RCU/{arrayRCU.txt => arrayRCU.rst} (91%) > > > > diff --git a/Documentation/RCU/arrayRCU.txt b/Documentation/RCU/arrayRCU.rst > > similarity index 91% > > rename from Documentation/RCU/arrayRCU.txt > > rename to Documentation/RCU/arrayRCU.rst > > index f05a9afb2c39..ed5ae24b196e 100644 > > --- a/Documentation/RCU/arrayRCU.txt > > +++ b/Documentation/RCU/arrayRCU.rst > > @@ -1,5 +1,7 @@ > > -Using RCU to Protect Read-Mostly Arrays > > +.. _array_rcu_doc: > > +Using RCU to Protect Read-Mostly Arrays > > +======================================= > > Although RCU is more commonly used to protect linked lists, it can > > also be used to protect arrays. Three situations are as follows: > > @@ -26,6 +28,7 @@ described in the following sections. > > It will be better to have the cross reference for each situation. > > Hash Tables > Static Arrays > Resizeable Arrays Madhuparna, could you please put a patch together creating these cross-references and handling Phong's comments below (probably by getting rid of the "." so that the resulting ":" doesn't look strange)? Then I will fold that patch into your original commit in -rcu and add Phong's Tested-by. Thanx, Paul > > Situation 1: Hash Tables > > +------------------------ > > Hash tables are often implemented as an array, where each array entry > > has a linked-list hash chain. Each hash chain can be protected by RCU > > @@ -34,6 +37,7 @@ to other array-of-list situations, such as radix trees. > > Situation 2: Static Arrays > > +-------------------------- > > Static arrays, where the data (rather than a pointer to the data) is > > located in each array element, and where the array is never resized, > > @@ -41,11 +45,13 @@ have not been used with RCU. Rik van Riel recommends using seqlock in > > this situation, which would also have minimal read-side overhead as long > > as updates are rare. > > -Quick Quiz: Why is it so important that updates be rare when > > - using seqlock? > > +Quick Quiz: > > + Why is it so important that updates be rare when using seqlock? > > +:ref:`Answer to Quick Quiz <answer_quick_quiz_seqlock>` > > Situation 3: Resizeable Arrays > > +------------------------------ > > Use of RCU for resizeable arrays is demonstrated by the grow_ary() > > function formerly used by the System V IPC code. The array is used > > @@ -60,7 +66,7 @@ the remainder of the new, updates the ids->entries pointer to point to > > the new array, and invokes ipc_rcu_putref() to free up the old array. > > Note that rcu_assign_pointer() is used to update the ids->entries pointer, > > which includes any memory barriers required on whatever architecture > > -you are running on. > > +you are running on.:: > > a redundant ":" in here with html page. > > > > > > static int grow_ary(struct ipc_ids* ids, int newsize) > > { > > @@ -112,7 +118,7 @@ a simple check suffices. The pointer to the structure corresponding > > to the desired IPC object is placed in "out", with NULL indicating > > a non-existent entry. After acquiring "out->lock", the "out->deleted" > > flag indicates whether the IPC object is in the process of being > > -deleted, and, if not, the pointer is returned. > > +deleted, and, if not, the pointer is returned.:: > > same as above > > > Tested-by: Phong Tran <tranmanphong@gmail.com> > > Regards, > Phong. > > > struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id) > > { > > @@ -144,8 +150,10 @@ deleted, and, if not, the pointer is returned. > > return out; > > } > > +.. _answer_quick_quiz_seqlock: > > Answer to Quick Quiz: > > + Why is it so important that updates be rare when using seqlock? > > The reason that it is important that updates be rare when > > using seqlock is that frequent updates can livelock readers. > > diff --git a/Documentation/RCU/index.rst b/Documentation/RCU/index.rst > > index 5c99185710fa..8d20d44f8fd4 100644 > > --- a/Documentation/RCU/index.rst > > +++ b/Documentation/RCU/index.rst > > @@ -7,6 +7,7 @@ RCU concepts > > .. toctree:: > > :maxdepth: 3 > > + arrayRCU > > rcu > > listRCU > > UP > > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH] Documentation: RCU: arrayRCU: Converted arrayRCU.txt to arrayRCU.rst 2019-11-05 14:04 ` Paul E. McKenney @ 2019-11-05 14:33 ` Amol Grover 2019-11-05 14:45 ` Paul E. McKenney 0 siblings, 1 reply; 6+ messages in thread From: Amol Grover @ 2019-11-05 14:33 UTC (permalink / raw) To: Paul E. McKenney Cc: Phong Tran, corbet, linux-doc, linux-kernel, rcu, joel, linux-kernel-mentees, madhuparnabhowmik04 On Tue, Nov 05, 2019 at 06:04:11AM -0800, Paul E. McKenney wrote: > On Tue, Nov 05, 2019 at 08:49:47PM +0700, Phong Tran wrote: > > On 10/29/19 3:24 AM, madhuparnabhowmik04@gmail.com wrote: > > > From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> > > > > > > This patch converts arrayRCU from txt to rst format. > > > arrayRCU.rst is also added in the index.rst file. > > > > > > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> > > > --- > > > .../RCU/{arrayRCU.txt => arrayRCU.rst} | 18 +++++++++++++----- > > > Documentation/RCU/index.rst | 1 + > > > 2 files changed, 14 insertions(+), 5 deletions(-) > > > rename Documentation/RCU/{arrayRCU.txt => arrayRCU.rst} (91%) > > > > > > diff --git a/Documentation/RCU/arrayRCU.txt b/Documentation/RCU/arrayRCU.rst > > > similarity index 91% > > > rename from Documentation/RCU/arrayRCU.txt > > > rename to Documentation/RCU/arrayRCU.rst > > > index f05a9afb2c39..ed5ae24b196e 100644 > > > --- a/Documentation/RCU/arrayRCU.txt > > > +++ b/Documentation/RCU/arrayRCU.rst > > > @@ -1,5 +1,7 @@ > > > -Using RCU to Protect Read-Mostly Arrays > > > +.. _array_rcu_doc: > > > +Using RCU to Protect Read-Mostly Arrays > > > +======================================= > > > Although RCU is more commonly used to protect linked lists, it can > > > also be used to protect arrays. Three situations are as follows: > > > @@ -26,6 +28,7 @@ described in the following sections. > > > > It will be better to have the cross reference for each situation. > > > > Hash Tables > > Static Arrays > > Resizeable Arrays > > Madhuparna, could you please put a patch together creating these > cross-references and handling Phong's comments below (probably > by getting rid of the "." so that the resulting ":" doesn't look > strange)? > > Then I will fold that patch into your original commit in -rcu and > add Phong's Tested-by. > > Thanx, Paul > > > > Situation 1: Hash Tables > > > +------------------------ > > > Hash tables are often implemented as an array, where each array entry > > > has a linked-list hash chain. Each hash chain can be protected by RCU > > > @@ -34,6 +37,7 @@ to other array-of-list situations, such as radix trees. > > > Situation 2: Static Arrays > > > +-------------------------- > > > Static arrays, where the data (rather than a pointer to the data) is > > > located in each array element, and where the array is never resized, > > > @@ -41,11 +45,13 @@ have not been used with RCU. Rik van Riel recommends using seqlock in > > > this situation, which would also have minimal read-side overhead as long > > > as updates are rare. > > > -Quick Quiz: Why is it so important that updates be rare when > > > - using seqlock? > > > +Quick Quiz: > > > + Why is it so important that updates be rare when using seqlock? > > > +:ref:`Answer to Quick Quiz <answer_quick_quiz_seqlock>` > > > Situation 3: Resizeable Arrays > > > +------------------------------ > > > Use of RCU for resizeable arrays is demonstrated by the grow_ary() > > > function formerly used by the System V IPC code. The array is used > > > @@ -60,7 +66,7 @@ the remainder of the new, updates the ids->entries pointer to point to > > > the new array, and invokes ipc_rcu_putref() to free up the old array. > > > Note that rcu_assign_pointer() is used to update the ids->entries pointer, > > > which includes any memory barriers required on whatever architecture > > > -you are running on. > > > +you are running on.:: > > > > a redundant ":" in here with html page. > > > > > > > > > > > static int grow_ary(struct ipc_ids* ids, int newsize) > > > { > > > @@ -112,7 +118,7 @@ a simple check suffices. The pointer to the structure corresponding > > > to the desired IPC object is placed in "out", with NULL indicating > > > a non-existent entry. After acquiring "out->lock", the "out->deleted" > > > flag indicates whether the IPC object is in the process of being > > > -deleted, and, if not, the pointer is returned. > > > +deleted, and, if not, the pointer is returned.:: > > > > same as above > > > > > > Tested-by: Phong Tran <tranmanphong@gmail.com> > > > > Regards, > > Phong. > > > > > struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id) > > > { > > > @@ -144,8 +150,10 @@ deleted, and, if not, the pointer is returned. > > > return out; > > > } > > > +.. _answer_quick_quiz_seqlock: > > > Answer to Quick Quiz: > > > + Why is it so important that updates be rare when using seqlock? > > > The reason that it is important that updates be rare when > > > using seqlock is that frequent updates can livelock readers. > > > diff --git a/Documentation/RCU/index.rst b/Documentation/RCU/index.rst > > > index 5c99185710fa..8d20d44f8fd4 100644 > > > --- a/Documentation/RCU/index.rst > > > +++ b/Documentation/RCU/index.rst > > > @@ -7,6 +7,7 @@ RCU concepts > > > .. toctree:: > > > :maxdepth: 3 > > > + arrayRCU > > > rcu > > > listRCU > > > UP > > > > _______________________________________________ > Linux-kernel-mentees mailing list > Linux-kernel-mentees@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees Hey, There are a few instances in the document where words are emphasized. Example, -not- in the first paragraph. The previous emphasis was correct wrt txt format, but this could be converted to italicize/bold to keep up with the reST format. Other than this and what Phong suggested, everything looks good! Tested-by: Amol Grover <frextrite@gmail.com> Thank you Amol ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH] Documentation: RCU: arrayRCU: Converted arrayRCU.txt to arrayRCU.rst 2019-11-05 14:33 ` Amol Grover @ 2019-11-05 14:45 ` Paul E. McKenney 0 siblings, 0 replies; 6+ messages in thread From: Paul E. McKenney @ 2019-11-05 14:45 UTC (permalink / raw) To: Amol Grover Cc: Phong Tran, corbet, linux-doc, linux-kernel, rcu, joel, linux-kernel-mentees, madhuparnabhowmik04 On Tue, Nov 05, 2019 at 08:03:44PM +0530, Amol Grover wrote: > On Tue, Nov 05, 2019 at 06:04:11AM -0800, Paul E. McKenney wrote: > > On Tue, Nov 05, 2019 at 08:49:47PM +0700, Phong Tran wrote: > > > On 10/29/19 3:24 AM, madhuparnabhowmik04@gmail.com wrote: > > > > From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> > > > > > > > > This patch converts arrayRCU from txt to rst format. > > > > arrayRCU.rst is also added in the index.rst file. > > > > > > > > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> > > > > --- > > > > .../RCU/{arrayRCU.txt => arrayRCU.rst} | 18 +++++++++++++----- > > > > Documentation/RCU/index.rst | 1 + > > > > 2 files changed, 14 insertions(+), 5 deletions(-) > > > > rename Documentation/RCU/{arrayRCU.txt => arrayRCU.rst} (91%) > > > > > > > > diff --git a/Documentation/RCU/arrayRCU.txt b/Documentation/RCU/arrayRCU.rst > > > > similarity index 91% > > > > rename from Documentation/RCU/arrayRCU.txt > > > > rename to Documentation/RCU/arrayRCU.rst > > > > index f05a9afb2c39..ed5ae24b196e 100644 > > > > --- a/Documentation/RCU/arrayRCU.txt > > > > +++ b/Documentation/RCU/arrayRCU.rst > > > > @@ -1,5 +1,7 @@ > > > > -Using RCU to Protect Read-Mostly Arrays > > > > +.. _array_rcu_doc: > > > > +Using RCU to Protect Read-Mostly Arrays > > > > +======================================= > > > > Although RCU is more commonly used to protect linked lists, it can > > > > also be used to protect arrays. Three situations are as follows: > > > > @@ -26,6 +28,7 @@ described in the following sections. > > > > > > It will be better to have the cross reference for each situation. > > > > > > Hash Tables > > > Static Arrays > > > Resizeable Arrays > > > > Madhuparna, could you please put a patch together creating these > > cross-references and handling Phong's comments below (probably > > by getting rid of the "." so that the resulting ":" doesn't look > > strange)? > > > > Then I will fold that patch into your original commit in -rcu and > > add Phong's Tested-by. > > > > Thanx, Paul > > > > > > Situation 1: Hash Tables > > > > +------------------------ > > > > Hash tables are often implemented as an array, where each array entry > > > > has a linked-list hash chain. Each hash chain can be protected by RCU > > > > @@ -34,6 +37,7 @@ to other array-of-list situations, such as radix trees. > > > > Situation 2: Static Arrays > > > > +-------------------------- > > > > Static arrays, where the data (rather than a pointer to the data) is > > > > located in each array element, and where the array is never resized, > > > > @@ -41,11 +45,13 @@ have not been used with RCU. Rik van Riel recommends using seqlock in > > > > this situation, which would also have minimal read-side overhead as long > > > > as updates are rare. > > > > -Quick Quiz: Why is it so important that updates be rare when > > > > - using seqlock? > > > > +Quick Quiz: > > > > + Why is it so important that updates be rare when using seqlock? > > > > +:ref:`Answer to Quick Quiz <answer_quick_quiz_seqlock>` > > > > Situation 3: Resizeable Arrays > > > > +------------------------------ > > > > Use of RCU for resizeable arrays is demonstrated by the grow_ary() > > > > function formerly used by the System V IPC code. The array is used > > > > @@ -60,7 +66,7 @@ the remainder of the new, updates the ids->entries pointer to point to > > > > the new array, and invokes ipc_rcu_putref() to free up the old array. > > > > Note that rcu_assign_pointer() is used to update the ids->entries pointer, > > > > which includes any memory barriers required on whatever architecture > > > > -you are running on. > > > > +you are running on.:: > > > > > > a redundant ":" in here with html page. > > > > > > > > > > > > > > > > static int grow_ary(struct ipc_ids* ids, int newsize) > > > > { > > > > @@ -112,7 +118,7 @@ a simple check suffices. The pointer to the structure corresponding > > > > to the desired IPC object is placed in "out", with NULL indicating > > > > a non-existent entry. After acquiring "out->lock", the "out->deleted" > > > > flag indicates whether the IPC object is in the process of being > > > > -deleted, and, if not, the pointer is returned. > > > > +deleted, and, if not, the pointer is returned.:: > > > > > > same as above > > > > > > > > > Tested-by: Phong Tran <tranmanphong@gmail.com> > > > > > > Regards, > > > Phong. > > > > > > > struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id) > > > > { > > > > @@ -144,8 +150,10 @@ deleted, and, if not, the pointer is returned. > > > > return out; > > > > } > > > > +.. _answer_quick_quiz_seqlock: > > > > Answer to Quick Quiz: > > > > + Why is it so important that updates be rare when using seqlock? > > > > The reason that it is important that updates be rare when > > > > using seqlock is that frequent updates can livelock readers. > > > > diff --git a/Documentation/RCU/index.rst b/Documentation/RCU/index.rst > > > > index 5c99185710fa..8d20d44f8fd4 100644 > > > > --- a/Documentation/RCU/index.rst > > > > +++ b/Documentation/RCU/index.rst > > > > @@ -7,6 +7,7 @@ RCU concepts > > > > .. toctree:: > > > > :maxdepth: 3 > > > > + arrayRCU > > > > rcu > > > > listRCU > > > > UP > > > > > > _______________________________________________ > > Linux-kernel-mentees mailing list > > Linux-kernel-mentees@lists.linuxfoundation.org > > https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees > > Hey, > There are a few instances in the document where words are > emphasized. Example, -not- in the first paragraph. The > previous emphasis was correct wrt txt format, but this > could be converted to italicize/bold to keep up with the > reST format. Other than this and what Phong suggested, > everything looks good! > > Tested-by: Amol Grover <frextrite@gmail.com> Thank you, Amol! Madhuparna, could you please also include a fix to the "-not-" text-emphasis issue (and any other occurrences) that Amol located? I can then add both Phong's and Amol's Tested-by. Thanx, Paul ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-11-05 14:45 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2019-10-28 20:24 [PATCH] Documentation: RCU: arrayRCU: Converted arrayRCU.txt to arrayRCU.rst madhuparnabhowmik04 2019-10-28 21:00 ` Paul E. McKenney 2019-11-05 13:49 ` [Linux-kernel-mentees] " Phong Tran 2019-11-05 14:04 ` Paul E. McKenney 2019-11-05 14:33 ` Amol Grover 2019-11-05 14:45 ` Paul E. McKenney
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