IB/hfi1: Get rid of divide when setting the tx request header
Div instructions show costly in profiles when the tx request header is set. Using right shift instead of a divide operation reduces the cycles spent in the function that sets the tx request header as shown in the profile. Use right shift operation instead. Profile before change: 43.24% 009 | |--23.41%-- user_sdma_send_pkts | | | |--99.90%-- hfi1_user_sdma_process_requestAfter: Profile after change: 45.75% 009 | |--14.81%-- user_sdma_send_pkts | | | |--99.95%-- hfi1_user_sdma_process_request Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com> Signed-off-by: Sebastian Sanchez <sebastian.sanchez@intel.com> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com> Signed-off-by: Doug Ledford <dledford@redhat.com>
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@ -143,7 +143,9 @@ MODULE_PARM_DESC(sdma_comp_size, "Size of User SDMA completion ring. Default: 12
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/* KDETH OM multipliers and switch over point */
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#define KDETH_OM_SMALL 4
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#define KDETH_OM_SMALL_SHIFT 2
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#define KDETH_OM_LARGE 64
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#define KDETH_OM_LARGE_SHIFT 6
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#define KDETH_OM_MAX_SIZE (1 << ((KDETH_OM_LARGE / KDETH_OM_SMALL) + 1))
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/* Tx request flag bits */
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@ -228,12 +230,6 @@ struct user_sdma_request {
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* size of the TID entry.
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*/
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u32 tidoffset;
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/*
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* KDETH.OM
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* Remember this because the header template always sets it
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* to 0.
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*/
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u8 omfactor;
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/*
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* We copy the iovs for this request (based on
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* info.iovcnt). These are only the data vectors
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@ -1323,6 +1319,7 @@ static int set_txreq_header(struct user_sdma_request *req,
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{
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struct hfi1_user_sdma_pkt_q *pq = req->pq;
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struct hfi1_pkt_header *hdr = &tx->hdr;
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u8 omfactor; /* KDETH.OM */
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u16 pbclen;
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int ret;
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u32 tidval = 0, lrhlen = get_lrh_len(*hdr, pad_len(datalen));
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@ -1400,8 +1397,9 @@ static int set_txreq_header(struct user_sdma_request *req,
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}
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tidval = req->tids[req->tididx];
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}
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req->omfactor = EXP_TID_GET(tidval, LEN) * PAGE_SIZE >=
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KDETH_OM_MAX_SIZE ? KDETH_OM_LARGE : KDETH_OM_SMALL;
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omfactor = EXP_TID_GET(tidval, LEN) * PAGE_SIZE >=
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KDETH_OM_MAX_SIZE ? KDETH_OM_LARGE_SHIFT :
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KDETH_OM_SMALL_SHIFT;
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/* Set KDETH.TIDCtrl based on value for this TID. */
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KDETH_SET(hdr->kdeth.ver_tid_offset, TIDCTRL,
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EXP_TID_GET(tidval, CTRL));
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@ -1416,12 +1414,12 @@ static int set_txreq_header(struct user_sdma_request *req,
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* transfer.
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*/
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SDMA_DBG(req, "TID offset %ubytes %uunits om%u",
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req->tidoffset, req->tidoffset / req->omfactor,
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req->omfactor != KDETH_OM_SMALL);
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req->tidoffset, req->tidoffset >> omfactor,
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omfactor != KDETH_OM_SMALL_SHIFT);
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KDETH_SET(hdr->kdeth.ver_tid_offset, OFFSET,
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req->tidoffset / req->omfactor);
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req->tidoffset >> omfactor);
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KDETH_SET(hdr->kdeth.ver_tid_offset, OM,
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req->omfactor != KDETH_OM_SMALL);
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omfactor != KDETH_OM_SMALL_SHIFT);
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}
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done:
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trace_hfi1_sdma_user_header(pq->dd, pq->ctxt, pq->subctxt,
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@ -1433,6 +1431,7 @@ static int set_txreq_header_ahg(struct user_sdma_request *req,
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struct user_sdma_txreq *tx, u32 len)
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{
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int diff = 0;
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u8 omfactor; /* KDETH.OM */
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struct hfi1_user_sdma_pkt_q *pq = req->pq;
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struct hfi1_pkt_header *hdr = &req->hdr;
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u16 pbclen = le16_to_cpu(hdr->pbc[0]);
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@ -1484,14 +1483,15 @@ static int set_txreq_header_ahg(struct user_sdma_request *req,
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}
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tidval = req->tids[req->tididx];
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}
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req->omfactor = ((EXP_TID_GET(tidval, LEN) *
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omfactor = ((EXP_TID_GET(tidval, LEN) *
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PAGE_SIZE) >=
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KDETH_OM_MAX_SIZE) ? KDETH_OM_LARGE :
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KDETH_OM_SMALL;
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KDETH_OM_MAX_SIZE) ? KDETH_OM_LARGE_SHIFT :
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KDETH_OM_SMALL_SHIFT;
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/* KDETH.OM and KDETH.OFFSET (TID) */
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AHG_HEADER_SET(req->ahg, diff, 7, 0, 16,
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((!!(req->omfactor - KDETH_OM_SMALL)) << 15 |
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((req->tidoffset / req->omfactor) & 0x7fff)));
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((!!(omfactor - KDETH_OM_SMALL_SHIFT)) << 15 |
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((req->tidoffset >> omfactor)
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& 0x7fff)));
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/* KDETH.TIDCtrl, KDETH.TID, KDETH.Intr, KDETH.SH */
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val = cpu_to_le16(((EXP_TID_GET(tidval, CTRL) & 0x3) << 10) |
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(EXP_TID_GET(tidval, IDX) & 0x3ff));
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