On Thu, Apr 11, 2013 at 10:13:42AM -0700, Dan Magenheimer wrote: >> From: Wanpeng Li [mailto:liwanp@xxxxxxxxxxxxxxxxxx] >> Subject: [PATCH 02/10] staging: zcache: remove zcache_freeze >> >> The default value of zcache_freeze is false and it won't be modified by >> other codes. Remove zcache_freeze since no routine can disable zcache >> during system running. >> >> Signed-off-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx> > >I'd prefer to leave this code in place as it may be very useful >if/when zcache becomes more tightly integrated into the MM subsystem >and the rest of the kernel. And the subtleties for temporarily disabling >zcache (which is what zcache_freeze does) are non-obvious and >may cause data loss so if someone wants to add this functionality >back in later and don't have this piece of code, it may take >a lot of pain to get it working. > >Usage example: All CPUs are fully saturated so it is questionable >whether spending CPU cycles for compression is wise. Kernel >could disable zcache using zcache_freeze. (Yes, a new entry point >would need to be added to enable/disable zcache_freeze.) > >My two cents... others are welcome to override. > Fair enough. ;-) Regards, Wanpeng Li >> --- >> drivers/staging/zcache/zcache-main.c | 55 +++++++++++----------------------- >> 1 file changed, 18 insertions(+), 37 deletions(-) >> >> diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c >> index e23d814..fe6801a 100644 >> --- a/drivers/staging/zcache/zcache-main.c >> +++ b/drivers/staging/zcache/zcache-main.c >> @@ -1118,15 +1118,6 @@ free_and_out: >> #endif /* CONFIG_ZCACHE_WRITEBACK */ >> >> /* >> - * When zcache is disabled ("frozen"), pools can be created and destroyed, >> - * but all puts (and thus all other operations that require memory allocation) >> - * must fail. If zcache is unfrozen, accepts puts, then frozen again, >> - * data consistency requires all puts while frozen to be converted into >> - * flushes. >> - */ >> -static bool zcache_freeze; >> - >> -/* >> * This zcache shrinker interface reduces the number of ephemeral pageframes >> * used by zcache to approximately the same as the total number of LRU_FILE >> * pageframes in use, and now also reduces the number of persistent pageframes >> @@ -1221,44 +1212,34 @@ int zcache_put_page(int cli_id, int pool_id, struct tmem_oid *oidp, >> { >> struct tmem_pool *pool; >> struct tmem_handle th; >> - int ret = -1; >> + int ret = 0; >> void *pampd = NULL; >> >> BUG_ON(!irqs_disabled()); >> pool = zcache_get_pool_by_id(cli_id, pool_id); >> if (unlikely(pool == NULL)) >> goto out; >> - if (!zcache_freeze) { >> - ret = 0; >> - th.client_id = cli_id; >> - th.pool_id = pool_id; >> - th.oid = *oidp; >> - th.index = index; >> - pampd = zcache_pampd_create((char *)page, size, raw, >> - ephemeral, &th); >> - if (pampd == NULL) { >> - ret = -ENOMEM; >> - if (ephemeral) >> - inc_zcache_failed_eph_puts(); >> - else >> - inc_zcache_failed_pers_puts(); >> - } else { >> - if (ramster_enabled) >> - ramster_do_preload_flnode(pool); >> - ret = tmem_put(pool, oidp, index, 0, pampd); >> - if (ret < 0) >> - BUG(); >> - } >> - zcache_put_pool(pool); >> + >> + th.client_id = cli_id; >> + th.pool_id = pool_id; >> + th.oid = *oidp; >> + th.index = index; >> + pampd = zcache_pampd_create((char *)page, size, raw, >> + ephemeral, &th); >> + if (pampd == NULL) { >> + ret = -ENOMEM; >> + if (ephemeral) >> + inc_zcache_failed_eph_puts(); >> + else >> + inc_zcache_failed_pers_puts(); >> } else { >> - inc_zcache_put_to_flush(); >> if (ramster_enabled) >> ramster_do_preload_flnode(pool); >> - if (atomic_read(&pool->obj_count) > 0) >> - /* the put fails whether the flush succeeds or not */ >> - (void)tmem_flush_page(pool, oidp, index); >> - zcache_put_pool(pool); >> + ret = tmem_put(pool, oidp, index, 0, pampd); >> + if (ret < 0) >> + BUG(); >> } >> + zcache_put_pool(pool); >> out: >> return ret; >> } >> -- >> 1.7.10.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>