I've ported Matthew's scsi RAM driver (originally posted in http://marc.info/?l=linux-scsi&m=120331663227540&w=2) to the 3.3 kernel. This could be useful for people interested in doing performance tests on the I/O stack and file system by emulating a very fast RAM speed scsi device. Thanks. Tim --- Signed-off-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> --- diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig index 16570aa..8aa2eae 100644 --- a/drivers/scsi/Kconfig +++ b/drivers/scsi/Kconfig @@ -1621,6 +1621,16 @@ config SCSI_DEBUG information. This driver is primarily of use to those testing the SCSI and block subsystems. If unsure, say N. +config SCSI_RAM + tristate "SCSI RAM-based host" + depends on SCSI + help + This driver simulates a host adapter with one disc attached. + The primary purpose of this driver is for performance testing + of the fs/block/scsi stack; as such it attempts to simulate a + disc which is as fast as RAM. If you are unsure how to answer + this question, say N. + config SCSI_MESH tristate "MESH (Power Mac internal SCSI) support" depends on PPC32 && PPC_PMAC && SCSI diff --git a/drivers/scsi/Makefile b/drivers/scsi/Makefile index 2b88749..394c1c4 100644 --- a/drivers/scsi/Makefile +++ b/drivers/scsi/Makefile @@ -157,6 +157,7 @@ obj-$(CONFIG_SCSI_OSD_INITIATOR) += osd/ # This goes last, so that "real" scsi devices probe earlier obj-$(CONFIG_SCSI_DEBUG) += scsi_debug.o +obj-$(CONFIG_SCSI_RAM) += scsi_ram.o obj-$(CONFIG_SCSI_WAIT_SCAN) += scsi_wait_scan.o diff --git a/drivers/scsi/scsi_ram.c b/drivers/scsi/scsi_ram.c new file mode 100644 index 0000000..d128050 --- /dev/null +++ b/drivers/scsi/scsi_ram.c @@ -0,0 +1,620 @@ +/* + * scsi_ram.c - A RAM-based SCSI driver for Linux. + * + * This driver is intended to run as fast as possible, hence the options + * to discard writes and reads. + * By default, it'll allocate half a gigabyte of RAM to use as a ramdisc; + * you can change this with the `capacity' module parameter. + * + * (C) Copyright 2012 Intel Corporation + * Author: Matthew Wilcox <willy@xxxxxxxxxxxxxxx> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; version 2 + * of the License. + */ + +#undef DEBUG + +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/kthread.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/spinlock.h> + +#include <scsi/scsi.h> +#include <scsi/scsi_cmnd.h> +#include <scsi/scsi_device.h> +#include <scsi/scsi_host.h> +#include <scsi/scsi_dbg.h> + +MODULE_LICENSE("GPL v2"); +MODULE_AUTHOR("Matthew Wilcox <willy@xxxxxxxxxxxxxxx>"); + +#define DRV_NAME "scsi_ram" + +static unsigned int sector_size = 512; +module_param(sector_size, uint, 0444); +MODULE_PARM_DESC(sector_size, "Size of sectors"); + +static unsigned int capacity = 1024 * 1024; +module_param(capacity, uint, 0444); +MODULE_PARM_DESC(capacity, "Number of logical blocks in device"); + +static int throw_away_writes; +module_param(throw_away_writes, int, 0644); +MODULE_PARM_DESC(throw_away_writes, "Discard all writes to the device"); + +static int throw_away_reads; +module_param(throw_away_reads, int, 0644); +MODULE_PARM_DESC(throw_away_reads, "Don't actually read data from the device"); + +static int use_thread = 1; +module_param(use_thread, int, 0644); +MODULE_PARM_DESC(use_thread, "Use a separate thread to do data accesses"); + +static void copy_buffer(struct scsi_cmnd *cmnd, char *buf, int len) +{ + char *p; + struct scatterlist *sg; + int i; + + scsi_for_each_sg(cmnd, sg, scsi_sg_count(cmnd), i) { + int tocopy = sg->length; + if (tocopy > len) + tocopy = len; + + p = kmap_atomic(sg_page(sg), KM_USER0); + memcpy(p + sg->offset, buf, tocopy); + kunmap_atomic(p, KM_USER0); + + len -= tocopy; + if (!len) + break; + buf += tocopy; + } + + scsi_set_resid(cmnd, len); +} + +static char inquiry[57] = { + 0, 0, 5, 0x22, 52, 0, 0, 0x0a, /* 0-7 */ + 'L', 'i', 'n', 'u', 'x', ' ', ' ', ' ', /* 8-15 */ + 'R', 'A', 'M', ' ', 'D', 'r', 'i', 'v', /* 16-23 */ + 'e', ' ', ' ', ' ', ' ', ' ', ' ', ' ', /* 24-31 */ + '0', '.', '0', '1', 0, 0, 0, 0, /* 32-39 */ + 0, 0, 0, 0, 0, 0, 0, 0, /* 40-47 */ + 0, 0, 0, 0, 0, 0, 0, 0, /* 48-55 */ + 0 /* 56 */ +}; + +static char report_luns[] = { + 0, 0, 0, 8, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0 +}; + +/* + * SCSI requires quantities to be written MSB. They're frequently misaligned, + * so don't mess about with cpu_to_beN, just access it byte-wise + */ +static void scsi_ram_put_u32(unsigned char *addr, unsigned int data) +{ + addr[0] = data >> 24; + addr[1] = data >> 16; + addr[2] = data >> 8; + addr[3] = data; +} + +static unsigned int scsi_ram_get_u16(unsigned char *addr) +{ + unsigned int data; + data = addr[0] << 8; + data |= addr[1]; + + return data; +} + +static unsigned int scsi_ram_get_u24(unsigned char *addr) +{ + unsigned int data; + data = addr[0] << 16; + data |= addr[1] << 8; + data |= addr[2]; + + return data; +} + +static unsigned int scsi_ram_get_u32(unsigned char *addr) +{ + unsigned int data; + data = addr[0] << 24; + data |= addr[1] << 16; + data |= addr[2] << 8; + data |= addr[3]; + + return data; +} + +static void scsi_ram_setup_sense(struct scsi_cmnd *cmnd, unsigned char key, + unsigned char asc, unsigned char ascq) +{ + if (0) { + cmnd->sense_buffer[0] = 0x72; + cmnd->sense_buffer[1] = key; + cmnd->sense_buffer[2] = asc; + cmnd->sense_buffer[3] = ascq; + cmnd->sense_buffer[7] = 0; + } else { + cmnd->sense_buffer[0] = 0x70; + cmnd->sense_buffer[1] = 0; + cmnd->sense_buffer[2] = key; + cmnd->sense_buffer[7] = 11; + cmnd->sense_buffer[12] = asc; + cmnd->sense_buffer[13] = ascq; + } +} + +static void scsi_ram_inquiry(struct scsi_cmnd *cmnd) +{ + if (cmnd->cmnd[1] & 1) { + switch (cmnd->cmnd[2]) { + default: + scsi_ram_setup_sense(cmnd, ILLEGAL_REQUEST, 0x24, 0); + cmnd->result = SAM_STAT_CHECK_CONDITION; + } + } else { + copy_buffer(cmnd, inquiry, sizeof(inquiry)); + } +} + +static void scsi_ram_read_capacity(struct scsi_cmnd *cmnd) +{ + char buf[8]; + scsi_ram_put_u32(buf, capacity - 1); + scsi_ram_put_u32(buf + 4, sector_size); + copy_buffer(cmnd, buf, sizeof(buf)); +} + +static void scsi_ram_mode_sense(struct scsi_cmnd *cmnd) +{ + +} + + +static struct page **scsi_ram_data_array; + +/* + * We could steal the pages we need from the requests as they come in, which + * is what rd.c does. However, that's not a realistic simulator of how a + * device would work. We want the request pages to get freed and go back into + * the page allocator. + */ +static int scsi_ram_alloc_data(void) +{ + unsigned long pages = capacity / PAGE_SIZE * sector_size; + unsigned int i; + + scsi_ram_data_array = kmalloc(pages * sizeof(void *), GFP_KERNEL); + if (!scsi_ram_data_array) + return -ENOMEM; + + for (i = 0; i < pages; i++) { + struct page *page = alloc_page(GFP_KERNEL | __GFP_HIGHMEM); + scsi_ram_data_array[i] = page; + + /* scsi_ram_free_data will be called on failure */ + if (!page) + return -ENOMEM; + clear_highpage(page); + } + + return 0; +} + +static void scsi_ram_free_data(void) +{ + unsigned long pages = capacity / PAGE_SIZE * sector_size; + unsigned int i; + + if (!scsi_ram_data_array) + return; + + for (i = 0; i < pages; i++) { + struct page *page = scsi_ram_data_array[i]; + if (!page) + break; + __free_page(page); + } + + kfree(scsi_ram_data_array); +} + +static void scsi_ram_too_big(struct scsi_cmnd *cmnd, unsigned int start, + unsigned int len) +{ + printk(KERN_WARNING, "Request exceeded device capacity! %u %u\n", start, len); + scsi_ram_setup_sense(cmnd, ILLEGAL_REQUEST, 0x21, 0); + cmnd->result = SAM_STAT_CHECK_CONDITION; +} + +static void *get_data_page(unsigned int pfn) +{ + return kmap_atomic(scsi_ram_data_array[pfn], KM_USER0); +} + +static void put_data_page(void *addr) +{ + kunmap_atomic(addr, KM_USER0); +} + +static void *get_sg_page(struct page *page) +{ + return kmap_atomic(page, KM_USER1); +} + +static void put_sg_page(void *addr) +{ + kunmap_atomic(addr, KM_USER1); +} + +static void scsi_ram_read(struct scsi_cmnd *cmnd, unsigned int startB, + unsigned int lenB) +{ + unsigned long start = startB * sector_size; + unsigned long len = lenB * sector_size; + struct scatterlist *sg; + unsigned i, from_off = start % PAGE_SIZE, data_pfn = start / PAGE_SIZE; + + if (startB > capacity || (startB + lenB) > capacity) + return scsi_ram_too_big(cmnd, startB, lenB); + + if (throw_away_reads) + return; + + scsi_for_each_sg(cmnd, sg, scsi_sg_count(cmnd), i) { + struct page *sgpage = sg_page(sg); + unsigned int to_off = sg->offset; + unsigned int sg_copy = sg->length; + if (sg_copy > len) + sg_copy = len; + len -= sg_copy; + + while (sg_copy > 0) { + char *vto, *vfrom; + unsigned int page_copy; + + if (from_off > to_off) + page_copy = PAGE_SIZE - from_off; + else + page_copy = PAGE_SIZE - to_off; + if (page_copy > sg_copy) + page_copy = sg_copy; + + vfrom = get_data_page(data_pfn); + vto = get_sg_page(sgpage); + memcpy(vto + to_off, vfrom + from_off, page_copy); + put_sg_page(vto); + put_data_page(vfrom); + + from_off += page_copy; + if (from_off == PAGE_SIZE) { + from_off = 0; + data_pfn++; + } + to_off += page_copy; + if (to_off == PAGE_SIZE) { + to_off = 0; + sgpage++; + } + sg_copy -= page_copy; + } + if (!len) + break; + } +} + +static void scsi_ram_write(struct scsi_cmnd *cmnd, unsigned int startB, + unsigned int lenB) +{ + unsigned long start = startB * sector_size; + unsigned long len = lenB * sector_size; + struct scatterlist *sg; + unsigned i, to_off = start % PAGE_SIZE, data_pfn = start / PAGE_SIZE; + + if (startB > capacity || (startB + lenB) > capacity) + return scsi_ram_too_big(cmnd, startB, lenB); + + if (throw_away_writes) + return; + + scsi_for_each_sg(cmnd, sg, scsi_sg_count(cmnd), i) { + struct page *sgpage = sg_page(sg); + unsigned int from_off = sg->offset; + unsigned int sg_copy = sg->length; + if (sg_copy > len) + sg_copy = len; + len -= sg_copy; + + while (sg_copy > 0) { + char *vto, *vfrom; + unsigned int page_copy; + + if (from_off > to_off) + page_copy = PAGE_SIZE - from_off; + else + page_copy = PAGE_SIZE - to_off; + if (page_copy > sg_copy) + page_copy = sg_copy; + + vfrom = get_sg_page(sgpage); + vto = get_data_page(data_pfn); + memcpy(vto + to_off, vfrom + from_off, page_copy); + put_data_page(vto); + put_sg_page(vfrom); + + from_off += page_copy; + if (from_off == PAGE_SIZE) { + from_off = 0; + sgpage++; + } + to_off += page_copy; + if (to_off == PAGE_SIZE) { + to_off = 0; + data_pfn++; + } + sg_copy -= page_copy; + } + if (!len) + break; + } +} + +static void scsi_ram_read_6(struct scsi_cmnd *cmnd) +{ + unsigned int first_block = scsi_ram_get_u24(cmnd->cmnd + 1) & 0x1fffff; + unsigned int length = cmnd->cmnd[4]; + if (!length) + length = 256; + scsi_ram_read(cmnd, first_block, length); +} + +static void scsi_ram_read_10(struct scsi_cmnd *cmnd) +{ + unsigned int first_block = scsi_ram_get_u32(cmnd->cmnd + 2); + unsigned int length = scsi_ram_get_u16(cmnd->cmnd + 7); + scsi_ram_read(cmnd, first_block, length); +} + +static void scsi_ram_write_6(struct scsi_cmnd *cmnd) +{ + unsigned int first_block = scsi_ram_get_u24(cmnd->cmnd + 1) & 0x1fffff; + unsigned int length = cmnd->cmnd[4]; + if (!length) + length = 256; + scsi_ram_write(cmnd, first_block, length); +} + +static void scsi_ram_write_10(struct scsi_cmnd *cmnd) +{ + unsigned int first_block = scsi_ram_get_u32(cmnd->cmnd + 2); + unsigned int length = scsi_ram_get_u16(cmnd->cmnd + 7); + scsi_ram_write(cmnd, first_block, length); +} + +static void scsi_ram_execute_command(struct scsi_cmnd *cmnd) +{ +#ifdef DEBUG + scsi_print_command(cmnd); +#endif + + switch (cmnd->cmnd[0]) { + case INQUIRY: + scsi_ram_inquiry(cmnd); + break; + case REPORT_LUNS: + copy_buffer(cmnd, report_luns, sizeof(report_luns)); + break; + case TEST_UNIT_READY: + cmnd->result = 0; + break; + case READ_CAPACITY: + scsi_ram_read_capacity(cmnd); + break; + case MODE_SENSE: + scsi_ram_mode_sense(cmnd); + break; + case READ_6: + scsi_ram_read_6(cmnd); + break; + case READ_10: + scsi_ram_read_10(cmnd); + break; + case WRITE_6: + scsi_ram_write_6(cmnd); + break; + case WRITE_10: + scsi_ram_write_10(cmnd); + break; + default: + cmnd->result = DID_ABORT << 16; + } + + cmnd->scsi_done(cmnd); +} + +struct scsi_ram_device { + struct list_head commands; + struct Scsi_Host *host; + struct task_struct *thread; +}; + +static struct scsi_ram_device *scsi_ram_devices[16]; + +/* Overrides scsi_pointer */ +struct scsi_ram_cmnd { + struct list_head queue; +}; + +static int scsi_ram_device_thread(void *data) +{ + struct scsi_ram_device *ram_device = data; + struct Scsi_Host *host = ram_device->host; + unsigned long flags; + + while (!kthread_should_stop()) { + struct scsi_cmnd *cmnd; + struct scsi_ram_cmnd *ram_cmnd; + + spin_lock_irqsave(host->host_lock, flags); + if (list_empty(&ram_device->commands)) { + set_current_state(TASK_INTERRUPTIBLE); + spin_unlock_irq(host->host_lock); + schedule(); + continue; + } + + ram_cmnd = list_first_entry(&ram_device->commands, + struct scsi_ram_cmnd, queue); + list_del(&ram_cmnd->queue); + spin_unlock_irqrestore(host->host_lock, flags); + + cmnd = container_of((struct scsi_pointer *)ram_cmnd, + struct scsi_cmnd, SCp); + scsi_ram_execute_command(cmnd); + } + __set_current_state(TASK_RUNNING); + + return 0; +} + +static int scsi_ram_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *cmnd) +{ + struct scsi_ram_cmnd *ram_cmnd = (void *)&cmnd->SCp; + struct scsi_ram_device *ram_device = scsi_ram_devices[cmnd->device->id]; + unsigned long flags; + + pr_debug("%s: Queueing command\n", DRV_NAME); + if (!ram_device) + goto bad_device; + + if (use_thread) { + spin_lock_irqsave(shost->host_lock, flags); + if (list_empty(&ram_device->commands)) + wake_up_process(ram_device->thread); + list_add_tail(&ram_cmnd->queue, &ram_device->commands); + spin_unlock_irqrestore(shost->host_lock, flags); + } else { + scsi_ram_execute_command(cmnd); + } + + return 0; + + bad_device: + cmnd->result = DID_BAD_TARGET << 16; + cmnd->scsi_done(cmnd); + return 0; +} + +static int scsi_ram_slave_alloc(struct scsi_device *sdev) +{ + struct scsi_ram_device *ram_device; + + pr_debug("%s: slave_alloc %d:%d\n", DRV_NAME, sdev->id, sdev->lun); + + /* For the moment, create only device 0, lun 0 */ + if (sdev->id != 0) + return 0; + if (sdev->lun != 0) + return 0; + + ram_device = kmalloc(sizeof(*ram_device), GFP_KERNEL); + if (!ram_device) + goto nomem; + INIT_LIST_HEAD(&ram_device->commands); + ram_device->host = sdev->host; + if (scsi_ram_alloc_data()) + goto nomem; + ram_device->thread = kthread_run(scsi_ram_device_thread, ram_device, + "scsi_ram_%d", sdev->id); + if (IS_ERR(ram_device->thread)) + goto nomem; + + scsi_ram_devices[sdev->id] = ram_device; + return 0; + + nomem: + scsi_ram_free_data(); + kfree(ram_device); + return -ENOMEM; +} + +static void scsi_ram_slave_destroy(struct scsi_device *sdev) +{ + struct scsi_ram_device *ram_device = scsi_ram_devices[sdev->id]; + + pr_debug("%s: slave_destroy %d:%d\n", DRV_NAME, sdev->id, sdev->lun); + if (!ram_device) + return; + if (sdev->lun != 0) + return; + + kthread_stop(ram_device->thread); + scsi_ram_free_data(); + kfree(ram_device); + scsi_ram_devices[sdev->id] = NULL; +} + +static int scsi_ram_eh_host_reset_handler(struct scsi_cmnd *scmd) +{ + pr_debug("%s: eh_host_reset_handler\n", DRV_NAME); + return 0; +} + +static struct scsi_host_template scsi_ram_template = { + .proc_name = DRV_NAME, + .name = DRV_NAME, + .queuecommand = scsi_ram_queuecommand, + .eh_host_reset_handler = scsi_ram_eh_host_reset_handler, + .slave_alloc = scsi_ram_slave_alloc, + .slave_destroy = scsi_ram_slave_destroy, + .can_queue = 64, + .this_id = 7, + .sg_tablesize = SG_ALL, + .max_sectors = 1024, + .cmd_per_lun = 64, + .skip_settle_delay = 1, + .use_clustering = DISABLE_CLUSTERING, +}; + +static struct Scsi_Host *scsi_ram_host; + +static int __init scsi_ram_init(void) +{ + int error; + + scsi_ram_host = scsi_host_alloc(&scsi_ram_template, 0); + if (!scsi_ram_host) + return -ENOMEM; + + error = scsi_add_host(scsi_ram_host, NULL); + if (error) + goto free_host; + + scsi_scan_host(scsi_ram_host); + return 0; + + free_host: + scsi_host_put(scsi_ram_host); + return error; +} + +static void __exit scsi_ram_exit(void) +{ + scsi_remove_host(scsi_ram_host); + scsi_host_put(scsi_ram_host); +} + +module_init(scsi_ram_init); +module_exit(scsi_ram_exit); -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
