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Subject[patch 08/11] GRU Driver - resource management
This file contains functions related to managing GRU resources provided
to the user. Examples include GRU context assignment, load, unload, migration, etc..


Signed-off-by: Jack Steiner <steiner@sgi.com>

---
drivers/misc/gru/grumain.c | 872 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 872 insertions(+)
Index: linux/drivers/misc/gru/grumain.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux/drivers/misc/gru/grumain.c 2008-06-09 13:53:05.896790426 -0500
@@ -0,0 +1,872 @@
+/*
+ * SN Platform GRU Driver
+ *
+ * DRIVER TABLE MANAGER + GRU CONTEXT LOAD/UNLOAD
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (c) 2008 Silicon Graphics, Inc. All Rights Reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/spinlock.h>
+#include <linux/sched.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include "gru.h"
+#include "grutables.h"
+#include "gruhandles.h"
+#include <asm/uv/uv_hub.h>
+
+unsigned long options __read_mostly;
+
+static struct device_driver gru_driver = {
+ .name = "gru"
+};
+
+static struct device gru_device = {
+ .bus_id = {0},
+ .driver = &gru_driver,
+};
+
+struct device *grudev = &gru_device;
+
+/*
+ * Select a gru fault map to be used by the current cpu. Note that
+ * multiple cpus may be using the same map.
+ * ZZZ should "shift" be used?? Depends on HT cpu numbering
+ * ZZZ should be inline but did not work on emulator
+ */
+int gru_cpu_fault_map_id(void)
+{
+ return uv_blade_processor_id() % GRU_NUM_TFM;
+}
+
+/*--------- ASID Management -------------------------------------------
+ *
+ * Initially, assign asids sequentially from MIN_ASID .. MAX_ASID.
+ * Once MAX is reached, flush the TLB & start over. However,
+ * some asids may still be in use. There won't be many (percentage wise) still
+ * in use. Search active contexts & determine the value of the first
+ * asid in use ("x"s below). Set "limit" to this value.
+ * This defines a block of assignable asids.
+ *
+ * When "limit" is reached, search forward from limit+1 and determine the
+ * next block of assignable asids.
+ *
+ * Repeat until MAX_ASID is reached, then start over again.
+ *
+ * Each time MAX_ASID is reached, increment the asid generation. Since
+ * the search for in-use asids only checks contexts with GRUs currently
+ * assigned, asids in some contexts will be missed. Prior to loading
+ * a context, the asid generation of the GTS asid is rechecked. If it
+ * doesn't match the current generation, a new asid will be assigned.
+ *
+ * 0---------------x------------x---------------------x----|
+ * ^-next ^-limit ^-MAX_ASID
+ *
+ * All asid manipulation & context loading/unloading is protected by the
+ * gs_lock.
+ */
+
+/* Hit the asid limit. Start over */
+static int gru_wrap_asid(struct gru_state *gru)
+{
+ gru_dbg(grudev, "gru %p\n", gru);
+ STAT(asid_wrap);
+ gru->gs_asid_gen++;
+ gru_flush_all_tlb(gru);
+ return MIN_ASID;
+}
+
+/* Find the next chunk of unused asids */
+static int gru_reset_asid_limit(struct gru_state *gru, int asid)
+{
+ int i, gid, inuse_asid, limit;
+
+ gru_dbg(grudev, "gru %p, asid 0x%x\n", gru, asid);
+ STAT(asid_next);
+ limit = MAX_ASID;
+ if (asid >= limit)
+ asid = gru_wrap_asid(gru);
+ gid = gru->gs_gid;
+again:
+ for (i = 0; i < GRU_NUM_CCH; i++) {
+ if (!gru->gs_gts[i])
+ continue;
+ inuse_asid = gru->gs_gts[i]->ts_gms->ms_asids[gid].mt_asid;
+ gru_dbg(grudev, "gru %p, inuse_asid 0x%x, cxtnum %d, gts %p\n",
+ gru, inuse_asid, i, gru->gs_gts[i]);
+ if (inuse_asid == asid) {
+ asid += ASID_INC;
+ if (asid >= limit) {
+ /*
+ * empty range: reset the range limit and
+ * start over
+ */
+ limit = MAX_ASID;
+ if (asid >= MAX_ASID)
+ asid = gru_wrap_asid(gru);
+ goto again;
+ }
+ }
+
+ if ((inuse_asid > asid) && (inuse_asid < limit))
+ limit = inuse_asid;
+ }
+ gru->gs_asid_limit = limit;
+ gru->gs_asid = asid;
+ gru_dbg(grudev, "gru %p, new asid 0x%x, new_limit 0x%x\n", gru, asid,
+ limit);
+ return asid;
+}
+
+/* Assign a new ASID to a thread context. */
+static int gru_assign_asid(struct gru_state *gru)
+{
+ int asid;
+
+ spin_lock(&gru->gs_asid_lock);
+ gru->gs_asid += ASID_INC;
+ asid = gru->gs_asid;
+ if (asid >= gru->gs_asid_limit)
+ asid = gru_reset_asid_limit(gru, asid);
+ spin_unlock(&gru->gs_asid_lock);
+
+ gru_dbg(grudev, "gru %p, asid 0x%x\n", gru, asid);
+ return asid;
+}
+
+/*
+ * Clear n bits in a word. Return a word indicating the bits that were cleared.
+ * Optionally, build an array of chars that contain the bit numbers allocated.
+ */
+static unsigned long reserve_resources(unsigned long *p, int n, int mmax,
+ char *idx)
+{
+ unsigned long bits = 0;
+ int i;
+
+ do {
+ i = find_first_bit(p, mmax);
+ if (i == mmax)
+ BUG();
+ __clear_bit(i, p);
+ __set_bit(i, &bits);
+ if (idx)
+ *idx++ = i;
+ } while (--n);
+ return bits;
+}
+
+unsigned long reserve_gru_cb_resources(struct gru_state *gru, int cbr_au_count,
+ char *cbmap)
+{
+ return reserve_resources(&gru->gs_cbr_map, cbr_au_count, GRU_CBR_AU,
+ cbmap);
+}
+
+unsigned long reserve_gru_ds_resources(struct gru_state *gru, int dsr_au_count,
+ char *dsmap)
+{
+ return reserve_resources(&gru->gs_dsr_map, dsr_au_count, GRU_DSR_AU,
+ dsmap);
+}
+
+static void reserve_gru_resources(struct gru_state *gru,
+ struct gru_thread_state *gts)
+{
+ gru->gs_active_contexts++;
+ gts->ts_cbr_map =
+ reserve_gru_cb_resources(gru, gts->ts_cbr_au_count,
+ gts->ts_cbr_idx);
+ gts->ts_dsr_map =
+ reserve_gru_ds_resources(gru, gts->ts_dsr_au_count, NULL);
+}
+
+static void free_gru_resources(struct gru_state *gru,
+ struct gru_thread_state *gts)
+{
+ gru->gs_active_contexts--;
+ gru->gs_cbr_map |= gts->ts_cbr_map;
+ gru->gs_dsr_map |= gts->ts_dsr_map;
+}
+
+/*
+ * Check if a GRU has sufficient free resources to satisfy an allocation
+ * request. Note: GRU locks may or may not be held when this is called. If
+ * not held, recheck after acquiring the appropriate locks.
+ *
+ * Returns 1 if sufficient resources, 0 if not
+ */
+static int check_gru_resources(struct gru_state *gru, int cbr_au_count,
+ int dsr_au_count, int max_active_contexts)
+{
+ return hweight64(gru->gs_cbr_map) >= cbr_au_count
+ && hweight64(gru->gs_dsr_map) >= dsr_au_count
+ && gru->gs_active_contexts < max_active_contexts;
+}
+
+/*
+ * TLB manangment requires tracking all GRU chiplets that have loaded a GSEG
+ * context.
+ */
+static int gru_load_mm_tracker(struct gru_state *gru, struct gru_mm_struct *gms,
+ int ctxnum)
+{
+ struct gru_mm_tracker *asids = &gms->ms_asids[gru->gs_gid];
+ unsigned short ctxbitmap = (1 << ctxnum);
+ int asid;
+
+ spin_lock(&gms->ms_asid_lock);
+ asid = asids->mt_asid;
+
+ if (asid == 0 || asids->mt_asid_gen != gru->gs_asid_gen) {
+ asid = gru_assign_asid(gru);
+ asids->mt_asid = asid;
+ asids->mt_asid_gen = gru->gs_asid_gen;
+ STAT(asid_new);
+ } else {
+ STAT(asid_reuse);
+ }
+
+ BUG_ON(asids->mt_ctxbitmap & ctxbitmap);
+ asids->mt_ctxbitmap |= ctxbitmap;
+ if (!test_bit(gru->gs_gid, gms->ms_asidmap))
+ __set_bit(gru->gs_gid, gms->ms_asidmap);
+ spin_unlock(&gms->ms_asid_lock);
+
+ gru_dbg(grudev,
+ "gru %x, gms %p, ctxnum 0x%d, asid 0x%x, asidmap 0x%lx\n",
+ gru->gs_gid, gms, ctxnum, asid, gms->ms_asidmap[0]);
+ return asid;
+}
+
+static void gru_unload_mm_tracker(struct gru_state *gru,
+ struct gru_mm_struct *gms, int ctxnum)
+{
+ struct gru_mm_tracker *asids;
+ unsigned short ctxbitmap;
+
+ asids = &gms->ms_asids[gru->gs_gid];
+ ctxbitmap = (1 << ctxnum);
+ spin_lock(&gms->ms_asid_lock);
+ BUG_ON((asids->mt_ctxbitmap & ctxbitmap) != ctxbitmap);
+ asids->mt_ctxbitmap ^= ctxbitmap;
+ gru_dbg(grudev, "gru %x, gms %p, ctxnum 0x%d, asidmap 0x%lx\n",
+ gru->gs_gid, gms, ctxnum, gms->ms_asidmap[0]);
+ spin_unlock(&gms->ms_asid_lock);
+}
+
+/*
+ * Decrement the reference count on a GTS structure. Free the structure
+ * if the reference count goes to zero.
+ */
+void gts_drop(struct gru_thread_state *gts)
+{
+ if (gts && atomic_dec_return(&gts->ts_refcnt) == 0) {
+ gru_drop_mmu_notifier(gts->ts_gms);
+ kfree(gts);
+ STAT(gts_free);
+ }
+}
+
+/*
+ * Locate the GTS structure for the current thread.
+ */
+static struct gru_thread_state *gru_find_current_gts_nolock(struct gru_vma_data
+ *vdata, int tsid)
+{
+ struct gru_thread_state *gts;
+
+ list_for_each_entry(gts, &vdata->vd_head, ts_next)
+ if (gts->ts_tsid == tsid)
+ return gts;
+ return NULL;
+}
+
+/*
+ * Allocate a thread state structure.
+ */
+static struct gru_thread_state *gru_alloc_gts(struct vm_area_struct *vma,
+ struct gru_vma_data *vdata,
+ int tsid)
+{
+ struct gru_thread_state *gts;
+ int bytes;
+
+ bytes = DSR_BYTES(vdata->vd_dsr_au_count) +
+ CBR_BYTES(vdata->vd_cbr_au_count);
+ bytes += sizeof(struct gru_thread_state);
+ gts = kzalloc(bytes, GFP_KERNEL);
+ if (!gts)
+ return NULL;
+
+ STAT(gts_alloc);
+ atomic_set(&gts->ts_refcnt, 1);
+ mutex_init(&gts->ts_ctxlock);
+ gts->ts_cbr_au_count = vdata->vd_cbr_au_count;
+ gts->ts_dsr_au_count = vdata->vd_dsr_au_count;
+ gts->ts_user_options = vdata->vd_user_options;
+ gts->ts_tsid = tsid;
+ gts->ts_user_options = vdata->vd_user_options;
+ gts->ts_ctxnum = NULLCTX;
+ gts->ts_mm = current->mm;
+ gts->ts_vma = vma;
+ gts->ts_tlb_int_select = -1;
+ gts->ts_gms = gru_register_mmu_notifier();
+ if (!gts->ts_gms)
+ goto err;
+
+ gru_dbg(grudev, "alloc vdata %p, new gts %p\n", vdata, gts);
+ return gts;
+
+err:
+ gts_drop(gts);
+ return NULL;
+}
+
+/*
+ * Allocate a vma private data structure.
+ */
+struct gru_vma_data *gru_alloc_vma_data(struct vm_area_struct *vma, int tsid)
+{
+ struct gru_vma_data *vdata = NULL;
+
+ vdata = kmalloc(sizeof(*vdata), GFP_KERNEL);
+ if (!vdata)
+ return NULL;
+
+ INIT_LIST_HEAD(&vdata->vd_head);
+ spin_lock_init(&vdata->vd_lock);
+ gru_dbg(grudev, "alloc vdata %p\n", vdata);
+ return vdata;
+}
+
+/*
+ * Find the thread state structure for the current thread.
+ */
+struct gru_thread_state *gru_find_thread_state(struct vm_area_struct *vma,
+ int tsid)
+{
+ struct gru_vma_data *vdata = vma->vm_private_data;
+ struct gru_thread_state *gts;
+
+ spin_lock(&vdata->vd_lock);
+ gts = gru_find_current_gts_nolock(vdata, tsid);
+ spin_unlock(&vdata->vd_lock);
+ gru_dbg(grudev, "vma %p, gts %p\n", vma, gts);
+ return gts;
+}
+
+/*
+ * Allocate a new thread state for a GSEG. Note that races may allow
+ * another thread to race to create a gts.
+ */
+struct gru_thread_state *gru_alloc_thread_state(struct vm_area_struct *vma,
+ int tsid)
+{
+ struct gru_vma_data *vdata = vma->vm_private_data;
+ struct gru_thread_state *gts, *ngts;
+
+ gts = gru_alloc_gts(vma, vdata, tsid);
+ if (!gts)
+ return NULL;
+
+ spin_lock(&vdata->vd_lock);
+ ngts = gru_find_current_gts_nolock(vdata, tsid);
+ if (ngts) {
+ gts_drop(gts);
+ gts = ngts;
+ STAT(gts_double_allocate);
+ } else {
+ list_add(&gts->ts_next, &vdata->vd_head);
+ }
+ spin_unlock(&vdata->vd_lock);
+ gru_dbg(grudev, "vma %p, gts %p\n", vma, gts);
+ return gts;
+}
+
+/*
+ * Free the GRU context assigned to the thread state.
+ */
+static void gru_free_gru_context(struct gru_thread_state *gts)
+{
+ struct gru_state *gru;
+
+ gru = gts->ts_gru;
+ gru_dbg(grudev, "gts %p, gru %p\n", gts, gru);
+
+ spin_lock(&gru->gs_lock);
+ gru->gs_gts[gts->ts_ctxnum] = NULL;
+ free_gru_resources(gru, gts);
+ BUG_ON(test_bit(gts->ts_ctxnum, &gru->gs_context_map) == 0);
+ __clear_bit(gts->ts_ctxnum, &gru->gs_context_map);
+ gts->ts_ctxnum = NULLCTX;
+ gts->ts_gru = NULL;
+ spin_unlock(&gru->gs_lock);
+
+ gts_drop(gts);
+ STAT(free_context);
+}
+
+/*
+ * Prefetching cachelines help hardware performance.
+ */
+static void prefetch_data(void *p, int num, int stride)
+{
+ while (num-- > 0) {
+ prefetchw(p);
+ p += stride;
+ }
+}
+
+static inline long gru_copy_handle(void *d, void *s)
+{
+ memcpy(d, s, GRU_HANDLE_BYTES);
+ return GRU_HANDLE_BYTES;
+}
+
+/* rewrite in assembly & use lots of prefetch */
+static void gru_load_context_data(void *save, void *grubase, int ctxnum,
+ unsigned long cbrmap, unsigned long dsrmap)
+{
+ void *gseg, *cb, *cbe;
+ unsigned long length;
+ int i, scr;
+
+ gseg = grubase + ctxnum * GRU_GSEG_STRIDE;
+ length = hweight64(dsrmap) * GRU_DSR_AU_BYTES;
+ prefetch_data(gseg + GRU_DS_BASE, length / GRU_CACHE_LINE_BYTES,
+ GRU_CACHE_LINE_BYTES);
+
+ cb = gseg + GRU_CB_BASE;
+ cbe = grubase + GRU_CBE_BASE;
+ for_each_cbr_in_allocation_map(i, &cbrmap, scr) {
+ prefetch_data(cb, 1, GRU_CACHE_LINE_BYTES);
+ prefetch_data(cbe + i * GRU_HANDLE_STRIDE, 1,
+ GRU_CACHE_LINE_BYTES);
+ cb += GRU_HANDLE_STRIDE;
+ }
+
+ cb = gseg + GRU_CB_BASE;
+ for_each_cbr_in_allocation_map(i, &cbrmap, scr) {
+ save += gru_copy_handle(cb, save);
+ save += gru_copy_handle(cbe + i * GRU_HANDLE_STRIDE, save);
+ cb += GRU_HANDLE_STRIDE;
+ }
+
+ memcpy(gseg + GRU_DS_BASE, save, length);
+}
+
+static void gru_unload_context_data(void *save, void *grubase, int ctxnum,
+ unsigned long cbrmap, unsigned long dsrmap)
+{
+ void *gseg, *cb, *cbe;
+ unsigned long length;
+ int i, scr;
+
+ gseg = grubase + ctxnum * GRU_GSEG_STRIDE;
+
+ cb = gseg + GRU_CB_BASE;
+ cbe = grubase + GRU_CBE_BASE;
+ for_each_cbr_in_allocation_map(i, &cbrmap, scr) {
+ save += gru_copy_handle(save, cb);
+ save += gru_copy_handle(save, cbe + i * GRU_HANDLE_STRIDE);
+ cb += GRU_HANDLE_STRIDE;
+ }
+ length = hweight64(dsrmap) * GRU_DSR_AU_BYTES;
+ memcpy(save, gseg + GRU_DS_BASE, length);
+}
+
+void gru_unload_context(struct gru_thread_state *gts, int savestate)
+{
+ struct gru_state *gru = gts->ts_gru;
+ struct gru_context_configuration_handle *cch;
+ int ctxnum = gts->ts_ctxnum;
+
+ zap_page_range(gts->ts_vma, UGRUADDR(gts), GRU_GSEG_PAGESIZE, NULL);
+ cch = GRU_CCH(gru->gs_gru_base_vaddr, ctxnum);
+
+ lock_cch_handle(cch);
+ if (cch_interrupt_sync(cch))
+ BUG();
+ gru_dbg(grudev, "gts %p\n", gts);
+
+ gru_unload_mm_tracker(gru, gts->ts_gms, gts->ts_ctxnum);
+ if (savestate)
+ gru_unload_context_data(gts->ts_gdata, gru->gs_gru_base_vaddr,
+ ctxnum, gts->ts_cbr_map,
+ gts->ts_dsr_map);
+
+ if (cch_deallocate(cch))
+ BUG();
+ gts->ts_force_unload = 0; /* ts_force_unload locked by CCH lock */
+ unlock_cch_handle(cch);
+
+ gru_free_gru_context(gts);
+ STAT(unload_context);
+}
+
+/*
+ * Load a GRU context by copying it from the thread data structure in memory
+ * to the GRU.
+ */
+static void gru_load_context(struct gru_thread_state *gts)
+{
+ struct gru_state *gru = gts->ts_gru;
+ struct gru_context_configuration_handle *cch;
+ int err, asid, ctxnum = gts->ts_ctxnum;
+
+ gru_dbg(grudev, "gts %p\n", gts);
+ cch = GRU_CCH(gru->gs_gru_base_vaddr, ctxnum);
+
+ lock_cch_handle(cch);
+ asid = gru_load_mm_tracker(gru, gts->ts_gms, gts->ts_ctxnum);
+ cch->tfm_fault_bit_enable =
+ (gts->ts_user_options == GRU_OPT_MISS_FMM_POLL
+ || gts->ts_user_options == GRU_OPT_MISS_FMM_INTR);
+ cch->tlb_int_enable = (gts->ts_user_options == GRU_OPT_MISS_FMM_INTR);
+ if (cch->tlb_int_enable) {
+ gts->ts_tlb_int_select = gru_cpu_fault_map_id();
+ cch->tlb_int_select = gts->ts_tlb_int_select;
+ }
+ cch->tfm_done_bit_enable = 0;
+ err = cch_allocate(cch, asid, gts->ts_cbr_map, gts->ts_dsr_map);
+ if (err) {
+ gru_dbg(grudev,
+ "err %d: cch %p, gts %p, cbr 0x%lx, dsr 0x%lx\n",
+ err, cch, gts, gts->ts_cbr_map, gts->ts_dsr_map);
+ BUG();
+ }
+
+ gru_load_context_data(gts->ts_gdata, gru->gs_gru_base_vaddr, ctxnum,
+ gts->ts_cbr_map, gts->ts_dsr_map);
+
+ if (cch_start(cch))
+ BUG();
+ unlock_cch_handle(cch);
+
+ STAT(load_context);
+}
+
+/*
+ * Update fields in an active CCH:
+ * - retarget interrupts on local blade
+ * - force a delayed context unload by clearing the CCH asids. This
+ * forces TLB misses for new GRU instructions. The context is unloaded
+ * when the next TLB miss occurs.
+ */
+static int gru_update_cch(struct gru_thread_state *gts, int int_select)
+{
+ struct gru_context_configuration_handle *cch;
+ struct gru_state *gru = gts->ts_gru;
+ int i, ctxnum = gts->ts_ctxnum, ret = 0;
+
+ cch = GRU_CCH(gru->gs_gru_base_vaddr, ctxnum);
+
+ lock_cch_handle(cch);
+ if (cch->state == CCHSTATE_ACTIVE) {
+ if (gru->gs_gts[gts->ts_ctxnum] != gts)
+ goto exit;
+ if (cch_interrupt(cch))
+ BUG();
+ if (int_select >= 0) {
+ gts->ts_tlb_int_select = int_select;
+ cch->tlb_int_select = int_select;
+ } else {
+ for (i = 0; i < 8; i++)
+ cch->asid[i] = 0;
+ cch->tfm_fault_bit_enable = 0;
+ cch->tlb_int_enable = 0;
+ gts->ts_force_unload = 1;
+ }
+ if (cch_start(cch))
+ BUG();
+ ret = 1;
+ }
+exit:
+ unlock_cch_handle(cch);
+ return ret;
+}
+
+/*
+ * Update CCH tlb interrupt select. Required when all the following is true:
+ * - task's GRU context is loaded into a GRU
+ * - task is using interrupt notification for TLB faults
+ * - task has migrated to a different cpu on the same blade where
+ * it was previously running.
+ */
+static int gru_retarget_intr(struct gru_thread_state *gts)
+{
+ if (gts->ts_tlb_int_select < 0
+ || gts->ts_tlb_int_select == gru_cpu_fault_map_id())
+ return 0;
+
+ gru_dbg(grudev, "retarget from %d to %d\n", gts->ts_tlb_int_select,
+ gru_cpu_fault_map_id());
+ return gru_update_cch(gts, gru_cpu_fault_map_id());
+}
+
+/*
+ * Try to unload the GRU context. Task has migrated to a different blade.
+ * Called on migration when locks could not be obtained to immediately unload
+ * the context.
+ */
+static int gru_delayed_unload_context(struct gru_thread_state *gts)
+{
+ gru_dbg(grudev, "migration unload context gts %p\n", gts);
+ return gru_update_cch(gts, -1);
+}
+
+/*
+ * Insufficient GRU resources available on the local blade. Steal a context from
+ * a process. This is a hack until a _real_ resource scheduler is written....
+ */
+#define next_ctxnum(n) ((n) < GRU_NUM_CCH - 2 ? (n) + 1 : 0)
+#define next_gru(b, g) (((g) < &(b)->bs_grus[GRU_CHIPLETS_PER_BLADE - 1]) ? \
+ ((g)+1) : &(b)->bs_grus[0])
+
+static void gru_steal_context(struct gru_thread_state *gts)
+{
+ struct gru_blade_state *blade;
+ struct gru_state *gru, *gru0;
+ struct gru_thread_state *ngts = NULL;
+ int ctxnum, ctxnum0, flag = 0, cbr, dsr;
+
+ cbr = gts->ts_cbr_au_count;
+ dsr = gts->ts_dsr_au_count;
+
+ preempt_disable();
+ blade = gru_base[uv_numa_blade_id()];
+ spin_lock(&blade->bs_lock);
+
+ ctxnum = next_ctxnum(blade->bs_lru_ctxnum);
+ gru = blade->bs_lru_gru;
+ if (ctxnum == 0)
+ gru = next_gru(blade, gru);
+ ctxnum0 = ctxnum;
+ gru0 = gru;
+ while (1) {
+ if (check_gru_resources(gru, cbr, dsr, GRU_NUM_CCH))
+ break;
+ spin_lock(&gru->gs_lock);
+ for (; ctxnum < GRU_NUM_CCH; ctxnum++) {
+ if (flag && gru == gru0 && ctxnum == ctxnum0)
+ break;
+ ngts = gru->gs_gts[ctxnum];
+ /*
+ * We are grabbing locks out of order, so trylock is
+ * needed. GTSs are usually not locked, so the odds of
+ * success are high. If trylock fails, try to steal a
+ * different GSEG.
+ */
+ if (ngts && mutex_trylock(&ngts->ts_ctxlock))
+ break;
+ ngts = NULL;
+ flag = 1;
+ }
+ spin_unlock(&gru->gs_lock);
+ if (ngts || (flag && gru == gru0 && ctxnum == ctxnum0))
+ break;
+ ctxnum = 0;
+ gru = next_gru(blade, gru);
+ }
+ blade->bs_lru_gru = gru;
+ blade->bs_lru_ctxnum = ctxnum;
+ spin_unlock(&blade->bs_lock);
+ preempt_enable();
+
+ if (ngts) {
+ STAT(steal_context);
+ ngts->ts_steal_jiffies = jiffies;
+ gru_unload_context(ngts, 1);
+ mutex_unlock(&ngts->ts_ctxlock);
+ } else {
+ STAT(steal_context_failed);
+ }
+ gru_dbg(grudev,
+ "stole gru %x, ctxnum %d from gts %p. Need cb %d, ds %d;"
+ " avail cb %ld, ds %ld\n",
+ gru->gs_gid, ctxnum, ngts, cbr, dsr, hweight64(gru->gs_cbr_map),
+ hweight64(gru->gs_dsr_map));
+}
+
+/*
+ * Scan the GRUs on the local blade & assign a GRU context.
+ */
+static struct gru_state *gru_assign_gru_context(struct gru_thread_state *gts)
+{
+ struct gru_state *gru, *grux;
+ int i, max_active_contexts;
+
+ preempt_disable();
+
+again:
+ gru = NULL;
+ max_active_contexts = GRU_NUM_CCH;
+ for_each_gru_on_blade(grux, uv_numa_blade_id(), i) {
+ if (check_gru_resources(grux, gts->ts_cbr_au_count,
+ gts->ts_dsr_au_count,
+ max_active_contexts)) {
+ gru = grux;
+ max_active_contexts = grux->gs_active_contexts;
+ if (max_active_contexts == 0)
+ break;
+ }
+ }
+
+ if (gru) {
+ spin_lock(&gru->gs_lock);
+ if (!check_gru_resources(gru, gts->ts_cbr_au_count,
+ gts->ts_dsr_au_count, GRU_NUM_CCH)) {
+ spin_unlock(&gru->gs_lock);
+ goto again;
+ }
+ reserve_gru_resources(gru, gts);
+ gts->ts_gru = gru;
+ gts->ts_ctxnum =
+ find_first_zero_bit(&gru->gs_context_map, GRU_NUM_CCH);
+ BUG_ON(gts->ts_ctxnum == GRU_NUM_CCH);
+ atomic_inc(&gts->ts_refcnt);
+ gru->gs_gts[gts->ts_ctxnum] = gts;
+ __set_bit(gts->ts_ctxnum, &gru->gs_context_map);
+ spin_unlock(&gru->gs_lock);
+
+ STAT(assign_context);
+ gru_dbg(grudev,
+ "gseg %p, gts %p, gru %x, ctx %d, cbr %d, dsr %d\n",
+ gseg_virtual_address(gts->ts_gru, gts->ts_ctxnum), gts,
+ gts->ts_gru->gs_gid, gts->ts_ctxnum,
+ gts->ts_cbr_au_count, gts->ts_dsr_au_count);
+ } else {
+ gru_dbg(grudev, "failed to allocate a GTS %s\n", "");
+ STAT(assign_context_failed);
+ }
+
+ preempt_enable();
+ return gru;
+}
+
+/*
+ * gru_nopage
+ *
+ * Map the user's GRU segment
+ */
+int gru_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ struct gru_thread_state *gts;
+ unsigned long paddr, vaddr;
+
+ vaddr = (unsigned long)vmf->virtual_address;
+ gru_dbg(grudev, "vma %p, vaddr 0x%lx (0x%lx)\n",
+ vma, vaddr, GSEG_BASE(vaddr));
+ STAT(nopfn);
+
+ gts = gru_find_thread_state(vma, TSID(vaddr, vma));
+ if (!gts)
+ return VM_FAULT_SIGBUS;
+
+again:
+ preempt_disable();
+ mutex_lock(&gts->ts_ctxlock);
+ if (gts->ts_gru) {
+ if (gts->ts_gru->gs_blade_id != uv_numa_blade_id()) {
+ STAT(migrated_nopfn_unload);
+ gru_unload_context(gts, 1);
+ } else {
+ if (gru_retarget_intr(gts))
+ STAT(migrated_nopfn_retarget);
+ }
+ }
+
+ if (!gts->ts_gru) {
+ while (!gru_assign_gru_context(gts)) {
+ mutex_unlock(&gts->ts_ctxlock);
+ preempt_enable();
+ schedule_timeout(GRU_ASSIGN_DELAY); /* true hack ZZZ */
+ if (gts->ts_steal_jiffies + GRU_STEAL_DELAY < jiffies)
+ gru_steal_context(gts);
+ goto again;
+ }
+ gru_load_context(gts);
+ paddr = gseg_physical_address(gts->ts_gru, gts->ts_ctxnum);
+ remap_pfn_range(vma, vaddr & ~(GRU_GSEG_PAGESIZE - 1),
+ paddr >> PAGE_SHIFT, GRU_GSEG_PAGESIZE,
+ vma->vm_page_prot);
+ }
+
+ mutex_unlock(&gts->ts_ctxlock);
+ preempt_enable();
+
+ return VM_FAULT_NOPAGE;
+}
+
+/*
+ * gru_migrate_task
+ *
+ * Task has migrated to a different blade or a different cpu on the same blade
+ */
+static int do_migrate_gts(struct gru_state *gru, struct gru_thread_state *gts,
+ int locked, int pbid, int bid)
+{
+ int again = 0;
+
+ /*
+ * Directly unloading the context is more efficient but requires
+ * grabbing locks out-of-order. If trylock fails, migrate using the
+ * slow method.
+ */
+ if (pbid == bid) {
+ if (gru_retarget_intr(gts))
+ STAT(migrated_retarget);
+ } else if (locked && mutex_trylock(&gts->ts_ctxlock)) {
+ spin_unlock(&gru->gs_lock);
+ gru_unload_context(gts, 1);
+ mutex_unlock(&gts->ts_ctxlock);
+ STAT(migrated_unload);
+ again = 1;
+ } else if (gru_delayed_unload_context(gts)) {
+ STAT(migrated_unload_delay);
+ }
+ return again;
+}
+
+void gru_migrate_task(int pcpu, int cpu)
+{
+ struct gru_state *gru;
+ struct gru_thread_state *gts;
+ struct gru_blade_state *blade;
+ struct mm_struct *mm = current->mm;
+ int pbid = uv_cpu_to_blade_id(pcpu), bid = uv_cpu_to_blade_id(cpu);
+ int locked = 0, ctxnum, scr;
+
+ STAT(migrate_check);
+ blade = gru_base[bid];
+ if (!blade || !mm)
+ return;
+
+again:
+ /*
+ * Directly unloading the context is more efficient but requires
+ * grabbing locks out-of-order. If trylock fails, migrate using
+ * the slow method.
+ */
+ if (!locked)
+ locked = down_read_trylock(&mm->mmap_sem);
+ for_each_gru_on_blade(gru, pbid, scr) {
+ spin_lock(&gru->gs_lock);
+ for_each_gts_on_gru(gts, gru, ctxnum)
+ if (gts->ts_tgid_owner == current->tgid && gts->ts_gru)
+ if (do_migrate_gts(gru, gts, locked, pbid, bid))
+ goto again;
+ spin_unlock(&gru->gs_lock);
+ }
+
+ if (locked)
+ up_read(&mm->mmap_sem);
+}
--
Thanks

Jack Steiner (steiner@sgi.com) 651-683-5302
Sr Principal Engineer SGI - Silicon Graphics, Inc.




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  Last update: 2008-06-09 23:17    [from the cache]
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