- mpiwg-persistence - mailman3.cels.anl.gov

Re: [mpiwg-persistence] MPI Persistent/Collective WGs Weekly Meeting
by Skjellum, Anthony 17 Jun '19

17 Jun '19

All: We are meeting this Wednesday, 10am Central time (USA)---- discussion of Partitioned Communication will be the main topic, led by Ryan. Thanks, Tony Anthony Skjellum, PhD Professor of Computer Science and Chair of Excellence Director, SimCenter University of Tennessee at Chattanooga (UTC) tony-skjellum(a)utc.edu [or skjellum(a)gmail.com] cell: 205-807-4968 ________________________________ From: Skjellum, Anthony Sent: Wednesday, October 11, 2017 7:04 AM To: mpiwg-persistence(a)lists.mpi-forum.org; mpiwg-coll(a)lists.mpi-forum.org Cc: puri(a)uab.edu; HOLMES Daniel; hjelmn(a)lanl.gov; Islam, Nusrat; Sridharan, Srinivas; Ryan Eric Grant; Zheng, Gengbin; pirkelbauer2(a)llnl.gov; Matthew G. F. Dosanjh; yanivbl(a)mellanox.com; 'Bland, Wesley'; Bayyapu, Neelima; m.a.ruefenacht(a)gmail.com Subject: MPI Persistent/Collective WGs Weekly Meeting When: Wednesday, June 19, 2019 10:00 AM-11:00 AM. Where: Now, we use only zoom meetings: Hi there, Anthony Skjellum is inviting you to a scheduled Zoom meeting. Topic: Anthony Skjellum's Personal Meeting Room Join from PC, Mac, Linux, iOS or Android: https://tennessee.zoom.us/j/9916910516 Or iPhone one-tap (US Toll): +16468769923,9916910516# or +16699006833,9916910516# Or Telephone: Dial: +1 646 876 9923 (US Toll) +1 669 900 6833 (US Toll) Meeting ID: 991 691 0516 International numbers available: https://zoom.us/u/acVk33oBeV Or an H.323/SIP room system: H.323: 162.255.37.11 (US West) or 162.255.36.11 (US East) Meeting ID: 991 691 0516 SIP: 9916910516(a)zoomcrc.com

1 0

Re: [mpiwg-persistence] MPI Persistent/Collective WGs Weekly Meeting
by Skjellum, Anthony 04 Jun '19

04 Jun '19

Everyone, we are meeting, and the topic is partitioned communication following up to Chicago. Tony Anthony Skjellum, PhD Professor of Computer Science and Chair of Excellence Director, SimCenter University of Tennessee at Chattanooga (UTC) tony-skjellum(a)utc.edu [or skjellum(a)gmail.com] cell: 205-807-4968 ________________________________ From: Skjellum, Anthony Sent: Wednesday, October 11, 2017 7:04 AM To: mpiwg-persistence(a)lists.mpi-forum.org; mpiwg-coll(a)lists.mpi-forum.org Cc: puri(a)uab.edu; HOLMES Daniel; hjelmn(a)lanl.gov; Islam, Nusrat; Sridharan, Srinivas; Ryan Eric Grant; Zheng, Gengbin; pirkelbauer2(a)llnl.gov; Matthew G. F. Dosanjh; yanivbl(a)mellanox.com; 'Bland, Wesley'; Bayyapu, Neelima; m.a.ruefenacht(a)gmail.com Subject: MPI Persistent/Collective WGs Weekly Meeting When: Wednesday, June 5, 2019 10:00 AM-11:00 AM. Where: Now, we use only zoom meetings: Hi there, Anthony Skjellum is inviting you to a scheduled Zoom meeting. Topic: Anthony Skjellum's Personal Meeting Room Join from PC, Mac, Linux, iOS or Android: https://tennessee.zoom.us/j/9916910516 Or iPhone one-tap (US Toll): +16468769923,9916910516# or +16699006833,9916910516# Or Telephone: Dial: +1 646 876 9923 (US Toll) +1 669 900 6833 (US Toll) Meeting ID: 991 691 0516 International numbers available: https://zoom.us/u/acVk33oBeV Or an H.323/SIP room system: H.323: 162.255.37.11 (US West) or 162.255.36.11 (US East) Meeting ID: 991 691 0516 SIP: 9916910516(a)zoomcrc.com

1 0

Re: [mpiwg-persistence] [EXTERNAL] Re: Notes from WG meeting 28th May 2019
by HOLMES Daniel 28 May '19

28 May '19

Hi Ryan, I noticed some other comments/suggestions not related to your recent feedback changes but I didn’t do a full review of the overall proposal. Most of the comments/suggestions I had on the wider proposal were word-smithing only and could be done between this meeting and the next without derailing the timeline. This means it is definitely worth going through the reading this meeting because it forces a line-by-line review of the whole thing. Cheers, Dan. — Dr Daniel Holmes PhD Applications Consultant in HPC Research d.holmes(a)epcc.ed.ac.uk<mailto:[email protected]> Phone: +44 (0) 131 651 3465 Mobile: +44 (0) 7940 524 088 Address: Room 2.09, Bayes Centre, 47 Potterrow, Central Area, Edinburgh, EH8 9BT — The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. — On 28 May 2019, at 22:34, Grant, Ryan Eric (-EXP) <regrant(a)sandia.gov<mailto:[email protected]>> wrote: Everyone, Here are the changes based on feedback from today. There are quite a few changes but overall it is far less text than we had before. I'd appreciate any feedback and any other sets of eyes on this for a sanity check. Thanks, Ryan ________________________________ From: HOLMES Daniel <d.holmes(a)epcc.ed.ac.uk<mailto:[email protected]>> Sent: Tuesday, May 28, 2019 7:32 PM To: Anthony Skjellum; Grant, Ryan Eric (-EXP) Cc: MPI WG Persistence working Group Subject: [EXTERNAL] Re: [mpiwg-persistence] Notes from WG meeting 28th May 2019 Hi all, After further discussion, one of the answers has changed. Question: how does datatype describe complex layouts? Answer: it does not - it is the same as I/O with eType == xfer_type and fileType == contig New answer: the {count, datatype} tuple specifies the type map for a single partition; that interpretation of the proposed parameters permits a straightforward generalisation to MPI_Psendv_init and MPI_Psendw_init, which allow the type map to be different for each partition. For MPI_Psendv_init, the count parameter becomes an array of counts (of length equal to the numPartitions parameter) that gives the type map for the Nth partition via an implicit MPI_Type_contiguous(count_array[N], xfer_type) construction. For MPI_Psendw_init, both the count and data type parameters become arrays (of length equal to the numPartitions parameter) that give the type map for the Nth partition via an implicit MPI_Type_contiguous(count_array[N], type_array[N]) construction. The W version would benefit from an additional of displacements for the same reason as for the existing W functions in MPI. These extension functions permit arbitrary partitioning in future but require a change to the proposed special-case functions. Note: this new interpretation of the existing parameters for MPI_Psend_init and MPI_Precv_init avoids the possibility of the user giving a number of partitions that does not work with the {count, data type} tuple, e.g. numPartitions = 3 count = 10 datatype = MPI_Type_contiguous(100, MPI_DOUBLE) With the previous interpretation of the input parameters (i.e. the {count, data type} tuple specifies the type map for all partitions combined), this means MPI must try to divide 1000 doubles into 3 equally sized partitions, which leads to buffer under-run situations or to mandating some input combinations are erroneous. With the new interpretation of the input parameters (i.e. the {count, data type} tuple specifies the type map for each partition), this means there are 3 partitions of 1000 doubles, i.e. 3000 doubles in total across all partitions. This is quite a fundamental change for a no-no vote, so it may result in the proposal being read (again) at the next face-to-face meeting. Cheers, Dan. — Dr Daniel Holmes PhD Applications Consultant in HPC Research d.holmes(a)epcc.ed.ac.uk<mailto:[email protected]> Phone: +44 (0) 131 651 3465 Mobile: +44 (0) 7940 524 088 Address: Room 2.09, Bayes Centre, 47 Potterrow, Central Area, Edinburgh, EH8 9BT — The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. — On 28 May 2019, at 18:27, Skjellum, Anthony <Tony-Skjellum(a)utc.edu<mailto:[email protected]>> wrote: Cool — all seem fixable :-) Anthony Skjellum, PhD 205-807-4968 On May 28, 2019, at 4:25 PM, HOLMES Daniel via mpiwg-persistence <mpiwg-persistence(a)lists.mpi-forum.org<mailto:[email protected]>> wrote: Hi Ryan, Here are my notes from the WG meeting today: Define channel - for all usages throughout the spec (existing and proposed). Example: use variables for tag, dest, etc parameters in the Psend_init call Example: use variables for tag, dest, etc parameters in the Precv_init call Example: typo for MPI_Pstart - should be MPI_Start and should not end with brace Example: typo for &xfer_type in the Psend_init call - use just xfer_type instead Example: typo for &xfer_type in the Precv_init call - use just xfer_type instead Example: typo for &request and &i in the Pready call - use just request and i instead Example: typo for &part in the Pwait call - use just part instead Question: can partitioned receive match with any other send than the partitioned send it matched with during initialisation? No. Question: how does datatype describe complex layouts? Answer: it does not - it is the same as I/O with eType == xfer_type and fileType == contig Suggestion: add an MPI_Info parameter to both MPI_Psend_init and MPI_Precv_init Example: typo for amp parallel for (the for is missing) Example: tasks need to use different values for i in Pready Suggestion: mandate exactly one call to Pready for each partition between start and wait Suggestion: partition parameters must be consistent - either int or MPI_Count Note: there is room for (and potential use-cases for) Psendv_init (Pavan’s case) and Psendw_init (Rich’s case) Cheers, Dan. — Dr Daniel Holmes PhD Applications Consultant in HPC Research d.holmes(a)epcc.ed.ac.uk<mailto:[email protected]> Phone: +44 (0) 131 651 3465 Mobile: +44 (0) 7940 524 088 Address: Room 2.09, Bayes Centre, 47 Potterrow, Central Area, Edinburgh, EH8 9BT — The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. — _______________________________________________ mpiwg-persistence mailing list mpiwg-persistence(a)lists.mpi-forum.org<mailto:[email protected]> https://lists.mpi-forum.org/mailman/listinfo/mpiwg-persistence <part.pdf>

1 0

Re: [mpiwg-persistence] [EXTERNAL] Re: Notes from WG meeting 28th May 2019
by Grant, Ryan Eric (-EXP) 28 May '19

28 May '19

Everyone, Here are the changes based on feedback from today. There are quite a few changes but overall it is far less text than we had before. I'd appreciate any feedback and any other sets of eyes on this for a sanity check. Thanks, Ryan ________________________________ From: HOLMES Daniel <d.holmes(a)epcc.ed.ac.uk> Sent: Tuesday, May 28, 2019 7:32 PM To: Anthony Skjellum; Grant, Ryan Eric (-EXP) Cc: MPI WG Persistence working Group Subject: [EXTERNAL] Re: [mpiwg-persistence] Notes from WG meeting 28th May 2019 Hi all, After further discussion, one of the answers has changed. Question: how does datatype describe complex layouts? Answer: it does not - it is the same as I/O with eType == xfer_type and fileType == contig New answer: the {count, datatype} tuple specifies the type map for a single partition; that interpretation of the proposed parameters permits a straightforward generalisation to MPI_Psendv_init and MPI_Psendw_init, which allow the type map to be different for each partition. For MPI_Psendv_init, the count parameter becomes an array of counts (of length equal to the numPartitions parameter) that gives the type map for the Nth partition via an implicit MPI_Type_contiguous(count_array[N], xfer_type) construction. For MPI_Psendw_init, both the count and data type parameters become arrays (of length equal to the numPartitions parameter) that give the type map for the Nth partition via an implicit MPI_Type_contiguous(count_array[N], type_array[N]) construction. The W version would benefit from an additional of displacements for the same reason as for the existing W functions in MPI. These extension functions permit arbitrary partitioning in future but require a change to the proposed special-case functions. Note: this new interpretation of the existing parameters for MPI_Psend_init and MPI_Precv_init avoids the possibility of the user giving a number of partitions that does not work with the {count, data type} tuple, e.g. numPartitions = 3 count = 10 datatype = MPI_Type_contiguous(100, MPI_DOUBLE) With the previous interpretation of the input parameters (i.e. the {count, data type} tuple specifies the type map for all partitions combined), this means MPI must try to divide 1000 doubles into 3 equally sized partitions, which leads to buffer under-run situations or to mandating some input combinations are erroneous. With the new interpretation of the input parameters (i.e. the {count, data type} tuple specifies the type map for each partition), this means there are 3 partitions of 1000 doubles, i.e. 3000 doubles in total across all partitions. This is quite a fundamental change for a no-no vote, so it may result in the proposal being read (again) at the next face-to-face meeting. Cheers, Dan. — Dr Daniel Holmes PhD Applications Consultant in HPC Research d.holmes(a)epcc.ed.ac.uk<mailto:[email protected]> Phone: +44 (0) 131 651 3465 Mobile: +44 (0) 7940 524 088 Address: Room 2.09, Bayes Centre, 47 Potterrow, Central Area, Edinburgh, EH8 9BT — The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. — On 28 May 2019, at 18:27, Skjellum, Anthony <Tony-Skjellum(a)utc.edu<mailto:[email protected]>> wrote: Cool — all seem fixable :-) Anthony Skjellum, PhD 205-807-4968 On May 28, 2019, at 4:25 PM, HOLMES Daniel via mpiwg-persistence <mpiwg-persistence(a)lists.mpi-forum.org<mailto:[email protected]>> wrote: Hi Ryan, Here are my notes from the WG meeting today: Define channel - for all usages throughout the spec (existing and proposed). Example: use variables for tag, dest, etc parameters in the Psend_init call Example: use variables for tag, dest, etc parameters in the Precv_init call Example: typo for MPI_Pstart - should be MPI_Start and should not end with brace Example: typo for &xfer_type in the Psend_init call - use just xfer_type instead Example: typo for &xfer_type in the Precv_init call - use just xfer_type instead Example: typo for &request and &i in the Pready call - use just request and i instead Example: typo for &part in the Pwait call - use just part instead Question: can partitioned receive match with any other send than the partitioned send it matched with during initialisation? No. Question: how does datatype describe complex layouts? Answer: it does not - it is the same as I/O with eType == xfer_type and fileType == contig Suggestion: add an MPI_Info parameter to both MPI_Psend_init and MPI_Precv_init Example: typo for amp parallel for (the for is missing) Example: tasks need to use different values for i in Pready Suggestion: mandate exactly one call to Pready for each partition between start and wait Suggestion: partition parameters must be consistent - either int or MPI_Count Note: there is room for (and potential use-cases for) Psendv_init (Pavan’s case) and Psendw_init (Rich’s case) Cheers, Dan. — Dr Daniel Holmes PhD Applications Consultant in HPC Research d.holmes(a)epcc.ed.ac.uk<mailto:[email protected]> Phone: +44 (0) 131 651 3465 Mobile: +44 (0) 7940 524 088 Address: Room 2.09, Bayes Centre, 47 Potterrow, Central Area, Edinburgh, EH8 9BT — The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. — _______________________________________________ mpiwg-persistence mailing list mpiwg-persistence(a)lists.mpi-forum.org<mailto:[email protected]> https://lists.mpi-forum.org/mailman/listinfo/mpiwg-persistence

1 0

Re: [mpiwg-persistence] Notes from WG meeting 28th May 2019
by HOLMES Daniel 28 May '19

28 May '19

Hi all, After further discussion, one of the answers has changed. Question: how does datatype describe complex layouts? Answer: it does not - it is the same as I/O with eType == xfer_type and fileType == contig New answer: the {count, datatype} tuple specifies the type map for a single partition; that interpretation of the proposed parameters permits a straightforward generalisation to MPI_Psendv_init and MPI_Psendw_init, which allow the type map to be different for each partition. For MPI_Psendv_init, the count parameter becomes an array of counts (of length equal to the numPartitions parameter) that gives the type map for the Nth partition via an implicit MPI_Type_contiguous(count_array[N], xfer_type) construction. For MPI_Psendw_init, both the count and data type parameters become arrays (of length equal to the numPartitions parameter) that give the type map for the Nth partition via an implicit MPI_Type_contiguous(count_array[N], type_array[N]) construction. The W version would benefit from an additional of displacements for the same reason as for the existing W functions in MPI. These extension functions permit arbitrary partitioning in future but require a change to the proposed special-case functions. Note: this new interpretation of the existing parameters for MPI_Psend_init and MPI_Precv_init avoids the possibility of the user giving a number of partitions that does not work with the {count, data type} tuple, e.g. numPartitions = 3 count = 10 datatype = MPI_Type_contiguous(100, MPI_DOUBLE) With the previous interpretation of the input parameters (i.e. the {count, data type} tuple specifies the type map for all partitions combined), this means MPI must try to divide 1000 doubles into 3 equally sized partitions, which leads to buffer under-run situations or to mandating some input combinations are erroneous. With the new interpretation of the input parameters (i.e. the {count, data type} tuple specifies the type map for each partition), this means there are 3 partitions of 1000 doubles, i.e. 3000 doubles in total across all partitions. This is quite a fundamental change for a no-no vote, so it may result in the proposal being read (again) at the next face-to-face meeting. Cheers, Dan. — Dr Daniel Holmes PhD Applications Consultant in HPC Research d.holmes(a)epcc.ed.ac.uk<mailto:[email protected]> Phone: +44 (0) 131 651 3465 Mobile: +44 (0) 7940 524 088 Address: Room 2.09, Bayes Centre, 47 Potterrow, Central Area, Edinburgh, EH8 9BT — The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. — On 28 May 2019, at 18:27, Skjellum, Anthony <Tony-Skjellum(a)utc.edu<mailto:[email protected]>> wrote: Cool — all seem fixable :-) Anthony Skjellum, PhD 205-807-4968 On May 28, 2019, at 4:25 PM, HOLMES Daniel via mpiwg-persistence <mpiwg-persistence(a)lists.mpi-forum.org<mailto:[email protected]>> wrote: Hi Ryan, Here are my notes from the WG meeting today: Define channel - for all usages throughout the spec (existing and proposed). Example: use variables for tag, dest, etc parameters in the Psend_init call Example: use variables for tag, dest, etc parameters in the Precv_init call Example: typo for MPI_Pstart - should be MPI_Start and should not end with brace Example: typo for &xfer_type in the Psend_init call - use just xfer_type instead Example: typo for &xfer_type in the Precv_init call - use just xfer_type instead Example: typo for &request and &i in the Pready call - use just request and i instead Example: typo for &part in the Pwait call - use just part instead Question: can partitioned receive match with any other send than the partitioned send it matched with during initialisation? No. Question: how does datatype describe complex layouts? Answer: it does not - it is the same as I/O with eType == xfer_type and fileType == contig Suggestion: add an MPI_Info parameter to both MPI_Psend_init and MPI_Precv_init Example: typo for amp parallel for (the for is missing) Example: tasks need to use different values for i in Pready Suggestion: mandate exactly one call to Pready for each partition between start and wait Suggestion: partition parameters must be consistent - either int or MPI_Count Note: there is room for (and potential use-cases for) Psendv_init (Pavan’s case) and Psendw_init (Rich’s case) Cheers, Dan. — Dr Daniel Holmes PhD Applications Consultant in HPC Research d.holmes(a)epcc.ed.ac.uk<mailto:[email protected]> Phone: +44 (0) 131 651 3465 Mobile: +44 (0) 7940 524 088 Address: Room 2.09, Bayes Centre, 47 Potterrow, Central Area, Edinburgh, EH8 9BT — The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. — _______________________________________________ mpiwg-persistence mailing list mpiwg-persistence(a)lists.mpi-forum.org<mailto:[email protected]> https://lists.mpi-forum.org/mailman/listinfo/mpiwg-persistence

1 0

Re: [mpiwg-persistence] Notes from WG meeting 28th May 2019
by Skjellum, Anthony 28 May '19

28 May '19

Cool — all seem fixable :-) Anthony Skjellum, PhD 205-807-4968 On May 28, 2019, at 4:25 PM, HOLMES Daniel via mpiwg-persistence <mpiwg-persistence(a)lists.mpi-forum.org<mailto:[email protected]>> wrote: Hi Ryan, Here are my notes from the WG meeting today: Define channel - for all usages throughout the spec (existing and proposed). Example: use variables for tag, dest, etc parameters in the Psend_init call Example: use variables for tag, dest, etc parameters in the Precv_init call Example: typo for MPI_Pstart - should be MPI_Start and should not end with brace Example: typo for &xfer_type in the Psend_init call - use just xfer_type instead Example: typo for &xfer_type in the Precv_init call - use just xfer_type instead Example: typo for &request and &i in the Pready call - use just request and i instead Example: typo for &part in the Pwait call - use just part instead Question: can partitioned receive match with any other send than the partitioned send it matched with during initialisation? No. Question: how does datatype describe complex layouts? Answer: it does not - it is the same as I/O with eType == xfer_type and fileType == contig Suggestion: add an MPI_Info parameter to both MPI_Psend_init and MPI_Precv_init Example: typo for amp parallel for (the for is missing) Example: tasks need to use different values for i in Pready Suggestion: mandate exactly one call to Pready for each partition between start and wait Suggestion: partition parameters must be consistent - either int or MPI_Count Note: there is room for (and potential use-cases for) Psendv_init (Pavan’s case) and Psendw_init (Rich’s case) Cheers, Dan. — Dr Daniel Holmes PhD Applications Consultant in HPC Research d.holmes(a)epcc.ed.ac.uk<mailto:[email protected]> Phone: +44 (0) 131 651 3465 Mobile: +44 (0) 7940 524 088 Address: Room 2.09, Bayes Centre, 47 Potterrow, Central Area, Edinburgh, EH8 9BT — The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. — _______________________________________________ mpiwg-persistence mailing list mpiwg-persistence(a)lists.mpi-forum.org<mailto:[email protected]> https://lists.mpi-forum.org/mailman/listinfo/mpiwg-persistence

1 0

Notes from WG meeting 28th May 2019
by HOLMES Daniel 28 May '19

28 May '19

Hi Ryan, Here are my notes from the WG meeting today: Define channel - for all usages throughout the spec (existing and proposed). Example: use variables for tag, dest, etc parameters in the Psend_init call Example: use variables for tag, dest, etc parameters in the Precv_init call Example: typo for MPI_Pstart - should be MPI_Start and should not end with brace Example: typo for &xfer_type in the Psend_init call - use just xfer_type instead Example: typo for &xfer_type in the Precv_init call - use just xfer_type instead Example: typo for &request and &i in the Pready call - use just request and i instead Example: typo for &part in the Pwait call - use just part instead Question: can partitioned receive match with any other send than the partitioned send it matched with during initialisation? No. Question: how does datatype describe complex layouts? Answer: it does not - it is the same as I/O with eType == xfer_type and fileType == contig Suggestion: add an MPI_Info parameter to both MPI_Psend_init and MPI_Precv_init Example: typo for amp parallel for (the for is missing) Example: tasks need to use different values for i in Pready Suggestion: mandate exactly one call to Pready for each partition between start and wait Suggestion: partition parameters must be consistent - either int or MPI_Count Note: there is room for (and potential use-cases for) Psendv_init (Pavan’s case) and Psendw_init (Rich’s case) Cheers, Dan. — Dr Daniel Holmes PhD Applications Consultant in HPC Research d.holmes(a)epcc.ed.ac.uk<mailto:[email protected]> Phone: +44 (0) 131 651 3465 Mobile: +44 (0) 7940 524 088 Address: Room 2.09, Bayes Centre, 47 Potterrow, Central Area, Edinburgh, EH8 9BT — The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. —

1 0

Canceled: MPI Persistent/Collective WGs Weekly Meeting
by Skjellum, Anthony 21 May '19

21 May '19

Not needed before MPI Forum

1 0

Canceled: MPI Persistent/Collective WGs Weekly Meeting
by Skjellum, Anthony 15 May '19

15 May '19

During MPI Forum, no meeting.

1 0

Canceled: MPI Persistent/Collective WGs Weekly Meeting
by Skjellum, Anthony 14 May '19

14 May '19

WE WILL MEET NEXT WEEK ON MAY 22 BEFORE THE MPI FORUM, BUT NOT MAY 15.

1 0