https://jira.whamcloud.com This file is an XML representation of an issue en-us 9.4.14 940014 05-12-2023 https://jira.whamcloud.com/browse/LU-14144 Lustre <p>A patch is needed to allow using "<tt>lctl set_param <span class="error">&#91;-P&#93;</span> mdt.*.max_mod_rpcs_per_client=N</tt>" and other module parameters via the normal Lustre parameter interface. It doesn't make sense that this is only available as a module parameter.</p> <p> </p> LU-14144

get and set Lustre module parameters via "lctl get_param/set_param"

Improvement Minor Open Unresolved WC Triage Jian Yu Fri, 20 Nov 2020 21:05:40 +0000 Fri, 15 Dec 2023 16:03:25 +0000 0 5 <p>It would also be possible to implement this with a symlink to the module parameter <tt>/sys/module/mdt/parameters/max_mod_rpcs_in_flight</tt>, similar to <tt>lnet_debugfs_symlinks</tt> does for <tt>debug_mb-&gt;"../../../module/libcfs/parameters/libcfs_debug_mb"</tt>.</p> <p>It also isn't clear why this parameter is limited by the MDT? AFAICS from the code, there doesn't appear to be any server-side limitation on the number of request slots used by a client, but I haven't done an exhaustive analysis.</p> <blockquote><p>It also isn't clear why this parameter is limited by the MDT? AFAICS from the code, there doesn't appear to be any server-side limitation on the number of request slots used by a client</p></blockquote> <p>The MDT side limit defines the maximum of the client max_mod_rpcs_in_flight. It is useful to have a max set server-side to prevent abuse by greedy clients.</p> <blockquote> <p>It would also be possible to implement this with a symlink to the module parameter <tt>/sys/module/mdt/parameters/max&#95;mod&#95;rpcs&#95;in&#95;flight</tt>, similar to "<tt>lnet&#95;debugfs&#95;symlinks does for debug_mb&#45;&gt;../../../module/libcfs/parameters/libcfs&#95;debug&#95;mb</tt>".</p></blockquote> <p>An alternate, and maybe preferable, solution would be to have "<tt>lctl get_param/set_param</tt>" look at "<tt>/sys/modules/&lt;obd&gt;/parameters/&lt;param&gt;</tt>" for parameters of the form "<tt>&lt;obd&gt;.&lt;param&gt;</tt>", which would immediately make all of the module parameters available for tuning via "<tt>lctl set&#95;param &#45;P</tt>".</p> <blockquote> <p>The MDT side limit defines the maximum of the client <tt>max&#95;mod&#95;rpcs&#95;in&#95;flight</tt>. It is useful to have a max set server-side to prevent abuse by greedy clients.</p></blockquote> <p>Sure. My main question is whether there are technical limitations (e.g. the number of slots in the <tt>last&#95;rcvd</tt> or <tt>reply&#95;data</tt> is hard-coded at mount time) that prevent this parameter from being changed at mount time on the MDS and/or allow clients to have different values (e.g. if the MDS value is updated, new clients mount and get new limit, but currently-mounted clients have old limit). </p> Related LU-5319 LU-13503 LU-16454 Development Rank 1|i01flb: Rank (Obsolete) 9223372036854775807