patch segpcache-maxwindow-is-useless

@@ -124,11 +124,10 @@
 /*
  * The following variables can be tuned via /etc/system.
  */
 
 int     segpcache_enabled = 1;          /* if 1, shadow lists are cached */
-pgcnt_t segpcache_maxwindow = 0;        /* max # of pages that can be cached */
 ulong_t segpcache_hashsize_win = 0;     /* # of non wired buckets */
 ulong_t segpcache_hashsize_wired = 0;   /* # of wired buckets */
 int     segpcache_reap_sec = 1;         /* reap check rate in secs */
 clock_t segpcache_reap_ticks = 0;       /* reap interval in ticks */
 int     segpcache_pcp_maxage_sec = 1;   /* pcp max age in secs */

@@ -147,18 +146,17 @@
 /*
  * Keep frequently used variables together in one cache line.
  */
 static struct p_ctrl1 {
         uint_t p_disabled;              /* if not 0, caching temporarily off */
-        pgcnt_t p_maxwin;               /* max # of pages that can be cached */
         size_t p_hashwin_sz;            /* # of non wired buckets */
         struct seg_phash *p_htabwin;    /* hash table for non wired entries */
         size_t p_hashwired_sz;          /* # of wired buckets */
         struct seg_phash_wired *p_htabwired; /* hash table for wired entries */
         kmem_cache_t *p_kmcache;        /* kmem cache for seg_pcache structs */
 #ifdef _LP64
-        ulong_t pad[1];
+        ulong_t pad[2];
 #endif /* _LP64 */
 } pctrl1;
 
 static struct p_ctrl2 {
         kmutex_t p_mem_mtx;     /* protects window counter and p_halinks */

@@ -179,11 +177,10 @@
         ulong_t pad[3];
 #endif /* _LP64 */
 } pctrl3;
 
 #define seg_pdisabled                   pctrl1.p_disabled
-#define seg_pmaxwindow                  pctrl1.p_maxwin
 #define seg_phashsize_win               pctrl1.p_hashwin_sz
 #define seg_phashtab_win                pctrl1.p_htabwin
 #define seg_phashsize_wired             pctrl1.p_hashwired_sz
 #define seg_phashtab_wired              pctrl1.p_htabwired
 #define seg_pkmcache                    pctrl1.p_kmcache

@@ -754,14 +751,10 @@
 
         if (IS_PFLAGS_WIRED(flags)) {
                 return (SEGP_SUCCESS);
         }
 
-        if (seg_plocked_window + btop(len) > seg_pmaxwindow) {
-                return (SEGP_FAIL);
-        }
-
         if (freemem < desfree) {
                 return (SEGP_FAIL);
         }
 
         return (SEGP_SUCCESS);

@@ -827,14 +820,10 @@
 
         ASSERT((len & PAGEOFFSET) == 0);
         npages = btop(len);
         mutex_enter(&seg_pmem_mtx);
         if (!IS_PFLAGS_WIRED(flags)) {
-                if (seg_plocked_window + npages > seg_pmaxwindow) {
-                        mutex_exit(&seg_pmem_mtx);
-                        return (SEGP_FAIL);
-                }
                 seg_plocked_window += npages;
         }
         seg_plocked += npages;
         mutex_exit(&seg_pmem_mtx);
 

@@ -946,11 +935,10 @@
         int hlinks = 0;
         int hlix;
         pcache_link_t *hlinkp;
         pcache_link_t *hlnextp = NULL;
         int lowmem;
-        int trim;
 
         ASSERT(seg_phashsize_win != 0);
 
         /*
          * if the cache is off or empty, return

@@ -959,11 +947,10 @@
                 return;
         }
 
         if (!force) {
                 lowmem = 0;
-                trim = 0;
                 if (freemem < lotsfree + needfree) {
                         spgcnt_t fmem = MAX((spgcnt_t)(freemem - needfree), 0);
                         if (fmem <= 5 * (desfree >> 2)) {
                                 lowmem = 1;
                         } else if (fmem <= 7 * (lotsfree >> 3)) {

@@ -976,14 +963,11 @@
                                     3 * (availrmem_initial >> 2)) {
                                         lowmem = 1;
                                 }
                         }
                 }
-                if (seg_plocked_window >= 7 * (seg_pmaxwindow >> 3)) {
-                        trim = 1;
-                }
-                if (!lowmem && !trim) {
+                if (!lowmem) {
                         return;
                 }
                 npgs_to_purge = seg_plocked_window >>
                     seg_pshrink_shift;
                 if (lowmem) {

@@ -1107,11 +1091,11 @@
                 }
                 if (!force) {
                         if (npgs_purged >= npgs_to_purge) {
                                 break;
                         }
-                        if (!trim && !(seg_pathr_full_ahb & 15)) {
+                        if (!(seg_pathr_full_ahb & 15)) {
                                 ASSERT(lowmem);
                                 if (freemem >= lotsfree + needfree) {
                                         break;
                                 }
                         }

@@ -1468,29 +1452,10 @@
                 hp->p_hnext = (struct seg_pcache *)hp;
                 hp->p_hprev = (struct seg_pcache *)hp;
                 mutex_init(&hp->p_hmutex, NULL, MUTEX_DEFAULT, NULL);
         }
 
-        if (segpcache_maxwindow == 0) {
-                if (physmegs < 64) {
-                        /* 3% of memory */
-                        segpcache_maxwindow = availrmem >> 5;
-                } else if (physmegs < 512) {
-                        /* 12% of memory */
-                        segpcache_maxwindow = availrmem >> 3;
-                } else if (physmegs < 1024) {
-                        /* 25% of memory */
-                        segpcache_maxwindow = availrmem >> 2;
-                } else if (physmegs < 2048) {
-                        /* 50% of memory */
-                        segpcache_maxwindow = availrmem >> 1;
-                } else {
-                        /* no limit */
-                        segpcache_maxwindow = (pgcnt_t)-1;
-                }
-        }
-        seg_pmaxwindow = segpcache_maxwindow;
         seg_pinit_mem_config();
 }
 
 /*
  * called by pageout if memory is low