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--- wiki:managing_resources_cpu_gpu [2019/11/19 17:56] – [Second scenario, more complex] neyron
+++ wiki:managing_resources_cpu_gpu [2020/03/03 13:43] – [First scenario, simple] neyron
@@ Line 11: / Line 11: @@
 In database these 4 kinds of resource properties are all stored as **columns** of the ''resources'' table. A rows then gives the set of properties for one resource.
-**Given a hierarchy** (chosen by the administrator for its cluster setup, for instance cluster/switch/host/cpu/core, but thread could be added, or other customizations), one row in the table gives information for the **lowest level of resources of the hierarchy** (e.g. core). Then **groups of lines** define higher levels, like Russian dolls (e.g. ''#C'' rows for CPUs, ''#H*#C'' rows for hosts, ...).
+**Given a hierarchy** (chosen by the administrator for his cluster setup, for instance cluster/switch/host/cpu/core, but thread could be added, or other customizations), one row in the table gives information for the **lowest level of resources of the hierarchy** (e.g. core). Then **groups of lines** define higher levels, like Russian dolls (e.g. ''#C'' rows for CPUs, ''#H*#C'' rows for hosts, ...).
 One rule must be kept in mind: **any unique object in the resources hierarchy must have a unique id among its set of object**. For example:
@@ Line 68: / Line 68: @@
 Also, if some nodes do not have any GPU, you could set the value of the property for the corresponding resources to ''gpudevice=-1'', and let the users add to the ''oarsub'' command a ''-p "gpudevice >=0"'' in order to get resources with GPUs.
+But be '''warned''', that the following commands will mostly not provide what a user would expect:
+<code bash>
+$ oarsub -l gpudevice=1
+</code>
+will gives all resources matching one identifier of gpudevices, which means all nodes limited to their first gpus (''gpudevice=0''), or second gpus (''gpudevice=1''), or all nodes which have no gpus (''gpudevice=-1'').
+<code bash>
+$ oarsub -l gpudevice=N
+</code>
+with N > 1 makes even less sense. See the setup proposed in the section below if you want to let your users request N gpus like that (using ''oarsub -l gpu=N'').
 ===== Second scenario, more complex =====
@@ Line 168: / Line 184: @@
 When reserving 1 GPU, the user obviously gets the 3 cores associated to the GPUs.
-GPU job can be tied to GPU resources (where ''gpu > 0'') with the following admission rule (see ''oaradmissionrules''), so that users don't have to set ''-p "gpu > 0"'' in their command lines:
+Finally, GPU jobs can be tied to GPU resources (where ''gpu > 0'') with the following admission rule (see ''oaradmissionrules''), so that users don't have to set ''-p "gpu > 0"'' in their command lines:
 <code perl>
 foreach my $mold (@{$ref_resource_list}){