default values are automatically set and are chosen to work well across a
number of typical scenarios.</para>
</note>
+ <section>
+ <title>ko2iblnd Tuning</title>
+ <para>The following table outlines the ko2iblnd module parameters to be used
+ for tuning:</para>
+ <informaltable frame="all">
+ <tgroup cols="3">
+ <colspec colname="c1" colwidth="50*" />
+ <colspec colname="c2" colwidth="50*" />
+ <colspec colname="c3" colwidth="50*" />
+ <thead>
+ <row>
+ <entry>
+ <para>
+ <emphasis role="bold">Module Parameter</emphasis>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <emphasis role="bold">Default Value</emphasis>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <emphasis role="bold">Description</emphasis>
+ </para>
+ </entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>
+ <para>
+ <literal>service</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>987</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Service number (within RDMA_PS_TCP).</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>cksum</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>0</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Set non-zero to enable message (not RDMA) checksums.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>timeout</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>50</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Timeout in seconds.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>nscheds</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>0</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Number of threads in each scheduler pool (per CPT). Value of
+ zero means we derive the number from the number of cores.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>conns_per_peer</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>4 (OmniPath), 1 (Everything else)</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Introduced in 2.10. Number of connections to each peer. Messages
+ are sent round-robin over the connection pool. Provides signifiant
+ improvement with OmniPath.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>ntx</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>512</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Number of message descriptors allocated for each pool at
+ startup. Grows at runtime. Shared by all CPTs.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>credits</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>256</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Number of concurrent sends on network.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>peer_credits</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>8</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Number of concurrent sends to 1 peer. Related/limited by IB
+ queue size.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>peer_credits_hiw</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>0</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>When eagerly to return credits.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>peer_buffer_credits</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>0</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Number per-peer router buffer credits.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>peer_timeout</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>180</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Seconds without aliveness news to declare peer dead (less than
+ or equal to 0 to disable).</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>ipif_name</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>ib0</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>IPoIB interface name.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>retry_count</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>5</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Retransmissions when no ACK received.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>rnr_retry_count</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>6</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>RNR retransmissions.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>keepalive</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>100</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Idle time in seconds before sending a keepalive.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>ib_mtu</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>0</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>IB MTU 256/512/1024/2048/4096.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>concurrent_sends</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>0</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Send work-queue sizing. If zero, derived from
+ <literal>map_on_demand</literal> and <literal>peer_credits</literal>.
+ </para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>map_on_demand</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>0 (pre-4.8 Linux) 1 (4.8 Linux onward) 32 (OmniPath)</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Number of fragments reserved for connection. If zero, use
+ global memory region (found to be security issue). If non-zero, use
+ FMR or FastReg for memory registration. Value needs to agree between
+ both peers of connection.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>fmr_pool_size</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>512</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Size of fmr pool on each CPT (>= ntx / 4). Grows at runtime.
+ </para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>fmr_flush_trigger</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>384</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Number dirty FMRs that triggers pool flush.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>fmr_cache</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>1</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Non-zero to enable FMR caching.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>dev_failover</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>0</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>HCA failover for bonding (0 OFF, 1 ON, other values reserved).
+ </para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>require_privileged_port</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>0</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Require privileged port when accepting connection.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>use_privileged_port</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>1</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Use privileged port when initiating connection.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para>
+ <literal>wrq_sge</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>
+ <literal>2</literal>
+ </para>
+ </entry>
+ <entry>
+ <para>Introduced in 2.10. Number scatter/gather element groups per
+ work request. Used to deal with fragmentations which can consume
+ double the number of work requests.</para>
+ </entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ </section>
</section>
<section xml:id="dbdoclet.nrstuning" condition='l24'>
<title>
<para>Beginning with Lustre 2.9, Lustre is extended to support RPCs up
to 16MB in size. By enabling a larger RPC size, fewer RPCs will be
required to transfer the same amount of data between clients and
- servers. With a larger RPC size, the OST can submit more data to the
+ servers. With a larger RPC size, the OSS can submit more data to the
underlying disks at once, therefore it can produce larger disk I/Os
to fully utilize the increasing bandwidth of disks.</para>
- <para>At client connecting time, clients will negotiate with
- servers for the RPC size it is going to use.</para>
- <para>A new parameter, <literal>brw_size</literal>, is introduced on
- the OST to tell the client the preferred IO size. All clients that
+ <para>At client connection time, clients will negotiate with
+ servers what the maximum RPC size it is possible to use, but the
+ client can always send RPCs smaller than this maximum.</para>
+ <para>The parameter <literal>brw_size</literal> is used on the OST
+ to tell the client the maximum (preferred) IO size. All clients that
talk to this target should never send an RPC greater than this size.
+ Clients can individually set a smaller RPC size limit via the
+ <literal>osc.*.max_pages_per_rpc</literal> tunable.
+ </para>
+ <note>
+ <para>The smallest <literal>brw_size</literal> that can be set for
+ ZFS OSTs is the <literal>recordsize</literal> of that dataset. This
+ ensures that the client can always write a full ZFS file block if it
+ has enough dirty data, and does not otherwise force it to do read-
+ modify-write operations for every RPC.
</para>
+ </note>
</section>
<section><title>Usage</title>
<para>In order to enable a larger RPC size,
<screen>client$ lctl conf_param <replaceable>fsname</replaceable>-OST*.osc.max_pages_per_rpc=16M</screen>
<caution><para>The <literal>brw_size</literal> of an OST can be
changed on the fly. However, clients have to be remounted to
- renegotiate the new RPC size.</para></caution>
+ renegotiate the new maximum RPC size.</para></caution>
</section>
</section>
<section xml:id="dbdoclet.50438272_80545">
git://git.whamcloud.com / doc / manual.git / blobdiff