<div dir="ltr">Hello Narendra,<div class="gmail_extra"><br><div class="gmail_quote">On Tue, Aug 1, 2017 at 6:19 PM, Narendra Pal Singh <span dir="ltr"><<a href="mailto:narendrapal2020@gmail.com" target="_blank">narendrapal2020@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><span style="font-size:12.8px">Hello,</span><div style="font-size:12.8px"><br></div><div style="font-size:12.8px">I have a server with bunch of SSD and HDD. i want to enable blk-mq for SSDs only as it gives negative performance for rotational disks. (Please correct me here if i required)</div><div style="font-size:12.8px"> <span style="color:rgb(51,51,51);font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace;font-size:14px;background-color:rgb(248,248,248)"> </span><br clear="all"><div>Is it possible to enable blk-mq for selective disks ? </div></div></div></blockquote><div>SSD and HDD are two kinds of devices which should be handled by two separate drivers. blk-mq is designed to exploit those IO controllers which can handle multiple requests in parallel. Also blk-mq increases the performance on devices where ramdom IO and sequencial IO performance doesn't have much difference. blk-mq will still do a bit of IO reordering to promote sequential access over random access. But since we have multiple queues, the magnitude of reorder is low in blk-mq.</div><div><br></div><div>So to answer to your question. Ideally it might have taken care in the drivers. No one will write a blk-mq model driver for HDD devices.</div><div><br></div><div>Regards,</div><div>Arun</div><div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><span class="HOEnZb"><font color="#888888"><div><br></div>-- <br><div class="m_-1208139886339337157gmail_signature"><div dir="ltr">Best Regards,<br>Narendra Pal Singh</div></div>
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