On Tue, 29 May 2007, Stephane Eranian wrote:
> --- linux-2.6.22.base/perfmon/perfmon_ctxsw.c 1969-12-31 16:00:00.000000000 -0800
> +++ linux-2.6.22/perfmon/perfmon_ctxsw.c 2007-05-29 03:24:14.000000000 -0700
> @@ -0,0 +1,341 @@
> +/*
> + * perfmon_cxtsw.c: perfmon2 context switch code
> + *
> + * This file implements the perfmon2 interface which
> + * provides access to the hardware performance counters
> + * of the host processor.
> + *
> + * The initial version of perfmon.c was written by
> + * Ganesh Venkitachalam, IBM Corp.
> + *
> + * Then it was modified for perfmon-1.x by Stephane Eranian and
> + * David Mosberger, Hewlett Packard Co.
> + *
> + * Version Perfmon-2.x is a complete rewrite of perfmon-1.x
> + * by Stephane Eranian, Hewlett Packard Co.
> + *
> + * Copyright (c) 1999-2006 Hewlett-Packard Development Company, L.P.
> + * Contributed by Stephane Eranian <[email protected]>
> + * David Mosberger-Tang <[email protected]>
> + *
> + * More information about perfmon available at:
> + * http://perfmon2.sf.net
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of version 2 of the GNU General Public
> + * License as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
> + * 02111-1307 USA
> + */
> +#include <linux/kernel.h>
> +#include <linux/perfmon.h>
> +
> +/*
> + * used only in UP mode
> + */
> +void pfm_save_prev_context(struct pfm_context *ctxp)
> +{
Is this comment still valid even though there's a call to this function in
the self-monitoring case in __pfm_load_context()?
> + struct pfm_event_set *set;
> +
> + /*
> + * in UP per-thread, due to lazy save
> + * there could be a context from another
> + * task. We need to push it first before
> + * installing our new state
> + */
> + set = ctxp->active_set;
> + pfm_modview_begin(set);
> + pfm_save_pmds(ctxp, set);
> + set->view->set_status &= ~PFM_SETVFL_ACTIVE;
> + pfm_modview_end(set);
> + /*
> + * do not clear ownership because we rewrite
> + * right away
> + */
> +}
> +
> +void pfm_save_pmds(struct pfm_context *ctx, struct pfm_event_set *set)
> +{
> + u64 val, hw_val, *pmds, ovfl_mask;
> + u64 *used_mask, *cnt_mask;
> + u16 i, num;
> +
> + ovfl_mask = pfm_pmu_conf->ovfl_mask;
> + num = set->nused_pmds;
> + cnt_mask = pfm_pmu_conf->cnt_pmds;
> + used_mask = set->used_pmds;
> + pmds = set->view->set_pmds;
> +
> + for (i = 0; num; i++) {
This should probably be "i++, num--".
> + if (test_bit(i, ulp(used_mask))) {
> + hw_val = val = pfm_read_pmd(ctx, i);
> + if (likely(test_bit(i, ulp(cnt_mask))))
> + val = (pmds[i] & ~ovfl_mask) |
> + (hw_val & ovfl_mask);
> + pmds[i] = val;
> + num--;
> + }
> + }
> +}
You can elimiate the hw_val automatic by eliminating its assignment and
replacing its use with val.
David
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